Add daily workflow for dependency pinning

This workflow automates the process of checking and pinning Python dependencies to stable versions that are at least two weeks old, creating a pull request with the updates.

.github/workflows/upgrade_deps.yml

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+name: Daily Dependency Pinning (2-Week Buffer)
+
+on:
+  schedule:
+    # Runs every day at midnight UTC
+    - cron: '0 0 * * *'
+  workflow_dispatch: # Allows you to trigger it manually from the UI
+
+jobs:
+  pin-deps:
+    runs-on: ubuntu-slim
+    permissions:
+      contents: write
+      pull-requests: write
+
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd
+
+      - name: Set up Python
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405
+        with:
+          python-version: '3.14'
+
+      - name: Calculate and pin two-week old stable versions
+        shell: python
+        run: |
+          import json
+          import urllib.request
+          import re
+          from datetime import datetime, timedelta, timezone
+          from pathlib import Path
+
+          toml_path = Path("pyproject.toml")
+          if not toml_path.exists():
+              print("pyproject.toml not found!")
+              exit(1)
+
+          content = toml_path.read_text(encoding="utf-8")
+          
+          # Regex to find standard dependencies under [project] dependencies = [ ... ]
+          # This handles lines like "urllib3>=1.26", "cryptography", etc. inside the array
+          dep_block_match = re.search(r'dependencies\s*=\s*\[(.*?)\]', content, re.DOTALL)
+          if not dep_block_match:
+              print("No standard project dependencies array found.")
+              exit(0)
+
+          dep_block = dep_block_match.group(1)
+          raw_deps = re.findall(r'"([^"]+)"', dep_block)
+          
+          updated_deps = []
+          two_weeks_ago = datetime.now(timezone.utc) - timedelta(days=14)
+
+          print(f"Evaluating dependencies against cutoff date: {two_weeks_ago.isoformat()}")
+
+          for dep in raw_deps:
+              # Isolate base package name (e.g., "urllib3>=1.25" -> "urllib3")
+              pkg_name = re.split(r'[<>=!~;]', dep)[0].strip()
+              
+              # Pull environment markers to re-attach later if they exist (e.g., ; sys_platform == 'win32')
+              marker = ""
+              if ";" in dep:
+                  marker = " ; " + dep.split(";", 1)[1].strip()
+
+              print(f"Fetching PyPI data for: {pkg_name}")
+              try:
+                  url = f"https://pypi.org/pypi/{pkg_name}/json"
+                  req = urllib.request.Request(url, headers={'User-Agent': 'GAM-CI-Script'})
+                  with urllib.request.urlopen(req) as response:
+                      data = json.loads(response.read().decode())
+                  
+                  valid_versions = []
+                  for ver, files in data.get("releases", {}).items():
+                      if not files:
+                          continue
+                      
+                      # Get upload time of the first file in the release
+                      upload_time_str = files[0].get("upload_time_iso_8601")
+                      if not upload_time_str:
+                          continue
+                      
+                      # Normalize trailing Z to +00:00 for Python's datetime parser
+                      if upload_time_str.endswith('Z'):
+                          upload_time_str = upload_time_str[:-1] + '+00:00'
+                      
+                      upload_time = datetime.fromisoformat(upload_time_str)
+                      
+                      # Filter: Must be older than 2 weeks and not a pre-release (alpha/beta/rc)
+                      if upload_time <= two_weeks_ago and not any(x in ver.lower() for x in ['a', 'b', 'rc', 'dev']):
+                          valid_versions.append((upload_time, ver))
+                  
+                  if valid_versions:
+                      # Sort by upload time descending to get the newest valid option
+                      valid_versions.sort(key=lambda x: x[0], reverse=True)
+                      target_version = valid_versions[0][1]
+                      
+                      pinned_dep = f"{pkg_name}=={target_version}{marker}"
+                      updated_deps.append(f'    "{pinned_dep}",')
+                      print(f"  -> Pinned to {target_version}")
+                  else:
+                      # Fallback to original line if no historical versions found
+                      updated_deps.append(f'    "{dep}",')
+                      
+              except Exception as e:
+                  print(f"  -> Error fetching package {pkg_name}: {e}. Keeping original constraint.")
+                  updated_deps.append(f'    "{dep}",')
+
+          # 2. Reconstruct the dependencies block in pyproject.toml
+          new_dep_block = "\n" + "\n".join(updated_deps) + "\n"
+          new_content = content.replace(dep_block_match.group(1), new_dep_block)
+          toml_path.write_text(new_content, encoding="utf-8")
+
+      - name: Create Pull Request
+        uses: peter-evans/create-pull-request@5f6978faf089d4d20b00c7766989d076bb2fc7f1
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          commit-message: "chore: upgrade PyPi deps"
+          title: "Upgrade PyPi deps"
+          body: "Automated scan checking PyPI for package versions at least 2 weeks old."
+          branch: sys-deps-upgrade
+          force: false # Standard push, plays nice with rulesets