use github.sha to get commit

Author: bisgaard-itis

.github/workflows/ci-testing-pull-request.yml

@@ -39,7 +39,7 @@ jobs:
       - name: Check openapi specs are up to date
         run: |
           if ! ./ci/github/helpers/openapi-specs-diff.bash diff \
-            https://raw.githubusercontent.com/${{ github.event.pull_request.head.repo.full_name }}/${{ github.event.pull_request.head.sha }} \
+            https://raw.githubusercontent.com/${{ github.event.pull_request.head.repo.full_name }}/${{ github.sha }} \
             .; then \
             echo "::error:: OAS are not up to date. Run 'make openapi-specs' to update them"; exit 1; \
           fi
@@ -59,7 +59,7 @@ jobs:
       - name: check api-server backwards compatibility
         run: |
           ./scripts/openapi-diff.bash breaking --fail-on ERR\
-            https://raw.githubusercontent.com/${{ github.event.pull_request.base.repo.full_name }}/${{ github.event.pull_request.head.sha }}/services/api-server/openapi.json \
+            https://raw.githubusercontent.com/${{ github.event.pull_request.base.repo.full_name }}/${{ github.sha }}/services/api-server/openapi.json \
             /specs/services/api-server/openapi.json
 
   all-oas-breaking:
@@ -78,5 +78,5 @@ jobs:
       - name: Check openapi-specs backwards compatibility
         run: |
           ./ci/github/helpers/openapi-specs-diff.bash breaking \
-            https://raw.githubusercontent.com/${{ github.event.pull_request.base.repo.full_name }}/${{ github.event.pull_request.head.sha }} \
+            https://raw.githubusercontent.com/${{ github.event.pull_request.base.repo.full_name }}/${{ github.sha }} \
             .