Fix variables building with CI on push

Author: pjcdawkins

.github/workflows/ci.yml

@@ -40,8 +40,8 @@ jobs:
 
     - name: Build platform.phar
       env:
-        CI_COMMIT_SHA: ${{ github.event.after }}
-        CI_COMMIT_REF_NAME: ${{ github.head_ref }}
+        CI_COMMIT_SHA: ${{ github.sha }}
+        CI_COMMIT_REF_NAME: ${{ github.ref_name }}
       run: |
         CI_COMMIT_SHORT_SHA=$(echo $CI_COMMIT_SHA | head -c8)
         ./bin/platform self:build --no-composer-rebuild --yes --replace-version "$CI_COMMIT_REF_NAME"-"$CI_COMMIT_SHORT_SHA" --output platform.phar