Apparently we refer to default environment variables differently

Signed-off-by: Gabriel Harris-Rouquette <gabizou@me.com>

.github/workflows/build-and-deploy.yaml

@@ -33,8 +33,8 @@ jobs:
         run: ./gradlew --refresh-dependencies -s clean build
         env:
           CI_SYSTEM: Github Actions
-          GIT_COMMIT: ${{ github.GITHUB_SHA }}
-          GIT_BRANCH: ${{ github.GITHUB_REF }}
+          GIT_COMMIT: ${{ GITHUB_SHA }}
+          GIT_BRANCH: ${{ GITHUB_REF }}
       - name: Add artifacts to build
         uses: actions/upload-artifact@v2
         with: