Rewrote license activation to use a lock to prevent race-conditions.

unity-project-cached/action.yaml

@@ -68,6 +68,7 @@ outputs:
 runs:
   using: "composite"
   steps:
+  # Note: I may want to add  the platform input to the cache key in the future if I want to cache per-platform. Though this will use more space.
   - name: "Get full cache key and build command."
     id: command
     run: |