fix: remove workflow files and pyproject.toml from release-please extra-files

GitHub Actions cannot modify .github/workflows/ files (403 "Resource not
accessible by integration"), causing "Error adding to tree" failure.
pyproject.toml is already handled natively by python release type.
Only Dockerfile needs the generic updater for x-release-please-version markers.

release-please-config.json

@@ -6,7 +6,11 @@
       "bump-patch-for-minor-pre-major": true,
       "include-component-in-tag": false,
       "extra-files": [
-        "pyproject.toml"
+        {
+          "type": "generic",
+          "path": "Dockerfile",
+          "glob": false
+        }
       ],
       "changelog-sections": [
         { "type": "feat", "section": "New Features" },