fix(ci): checking out non origin branch

Author: nbrugger-tgm

.github/workflows/test_action.yml

@@ -10,7 +10,8 @@ jobs:
     steps:
       - uses: actions/checkout@v2
         with:
-          ref: ${{ github.head_ref }}
+          ref: ${{github.event.pull_request.head.ref}} 
+          repository: ${{github.event.pull_request.head.repo.full_name}}
           fetch-depth: 0  # ensures that tags are fetched, seems to be needed
       - name: Capture commit id
         id: capture