[no ci] update secret decode tool

.github/actions/decrypt.sh

@@ -1,38 +1,11 @@
 #!/bin/sh
-credspath="$3"
+credspath="$1"
 if [ ! -d "$credspath" ]; then
     echo "creating ${credspath}"
     mkdir -p "$credspath"
 fi
-gpgfile="$1"
-if [ -f "$gpgfile" ]; then
-    echo "source file is ${gpgfile}"
-else
-    echo "ERROR: ${gpgfile} does not exist"
-    exit 1
-fi
-credsfile="$2"
-echo "target file is ${credsfile}"
-if [ -z ${PASSCODE+x} ]; then
-  echo "ERROR: PASSCODE is unset";
-  exit 2
-else
-  echo "PASSCODE is set";
-fi
 
-gpg --batch \
-    --yes \
-    --decrypt \
-    --passphrase="$PASSCODE" \
-    --output "$credsfile" \
-    "$gpgfile"
+secretvar="GAM_GHA_${JID}"
+secretval="${!secretvar}"
 
-if [[ "$RUNNER_OS" == "macOS" ]]; then
-  tar="gtar"
-else
-  tar="tar"
-fi
-
-"$tar" xlvvf "$credsfile" --directory "$credspath"
-rm -rvf "$gpgfile"
-rm -rvf "$credsfile"
+echo -e "$secretval" > "${credspath}/oauth2.txt"