only copy metadata for imports that exist

src/gam/__init__.py

@@ -6,10 +6,7 @@ import configparser
 import csv
 import datetime
 from email import message_from_string
-try:
-    from importlib.metadata import version as lib_version
-except ImportError:
-    from importlib_metadata import version as lib_version
+from importlib.metadata import version as lib_version
 import io
 import json
 import mimetypes