ops: Add back GITHUB_ENV usage

.gitea/workflows/ci.yml

@@ -98,12 +98,13 @@ jobs:
           mkdir -p "$staging"
           cp -r tests/unittest/build/artifacts/gcov "$staging"
           tar czf "$staging.tar.gz" "$staging"
+          echo "ASSET=$staging.tar.gz" >> $GITHUB_ENV
       -
         name: Archive artifacts
         uses: actions/upload-artifact@v3
         with:
           name: reports-${{gitea.run_number}}
-          path: reports-${{gitea.run_number}}.tar.gz
+          path: ${{ env.ASSET }}
           retention-days: 3
 
 # TODO: delete cache on merge.