Skip plus tests on a fork

Problem: The NGINX Plus JWT is only available on the upstream repo, so automated tests for Plus can't be run on forks.

Solution: Skip these test runs on a fork.

Author: sjberman

.github/workflows/functional.yml

@@ -21,6 +21,7 @@ jobs:
   functional-tests:
     name: Run Tests
     runs-on: ubuntu-24.04
+    if: (github.event.repository.fork == false) || (inputs.image != 'plus')
     env:
       DOCKER_BUILD_SUMMARY: false
     steps: