feat: add artifact upload step to GTFS update workflow

Author: 0xaa55h

.github/workflows/update.yml

@@ -39,5 +39,7 @@ jobs:
           cd gtfs-branch
           chmod +x gradlew
           ./gradlew updateGtfs --args="../input.zip ./files/$(date +'%Y-%m-%d').zip ../cache.tsv ${{ secrets.MAPYCZ_API_KEY }}"
+      - name: Upload artifact
+        run: : |
           cp ./files/$(date +'%Y-%m-%d').zip ./files/latest.zip
           git push https://${{ github.actor }}:${{ secrets.GITHUB_TOKEN }}@github.com/${{ github.repository }}.git gtfs