PYTHON-5047 Fix dry run logic in releases yet again (#2098)

Author: blink1073

.github/workflows/release-python.yml

@@ -23,7 +23,9 @@ env:
   SILK_ASSET_GROUP: mongodb-python-driver
   EVERGREEN_PROJECT: mongo-python-driver
   # Constant
-  DRY_RUN: ${{ github.event_name == 'workflow_dispatch' && inputs.dry_run || 'true' }}
+  # inputs will be empty on a scheduled run.  so, we only set dry_run
+  # to 'false' when the input is set to 'false'.
+  DRY_RUN: ${{ ! contains(inputs.dry_run, 'false') }}
   FOLLOWING_VERSION: ${{ inputs.following_version || '' }}
   VERSION: ${{ inputs.version || '10.10.10.10' }}