ci: update Docker build context and path in Forgejo release sync workflow

.gitea/workflows/run-forgejo-release-sync.yml

@@ -37,8 +37,8 @@ jobs:
       - name: Build image
         uses: docker/build-push-action@v7
         with:
-          context: ForgejoReleaseSync
-          file:    ForgejoReleaseSync/Dockerfile
+          context: .
+          file:    Dockerfile
           push:    false
           load:    true
           tags:    forgejo-release-sync:latest