fix: Use PR head commit in artifact naming instead of merge commit

The env var GITHUB_SHA shows merge commit and is not related to worflow trigger unlike the discription on GITHUB. This fix changes the variable to look at the head commit aka. the commit that actually triggers the workflow.

Author: bowenislandsong

.github/workflows/e2e-tests.yml

@@ -14,5 +14,5 @@ jobs:
         if: ${{ failure() }}
         uses: actions/upload-artifact@v2
         with:
-          name: e2e-test-output-${{ github.sha }}-${{ github.run_id }}
+          name: e2e-test-output-${{(github.event.pull_request.head.sha||github.sha)}}-${{ github.run_id }}
           path: ${{ github.workspace }}/bin/artifacts/*