Fix for build step

Author: 0x0BSoD

.github/workflows/docker.yaml

@@ -72,6 +72,7 @@ jobs:
           echo "date=$(date -u +'%Y-%m-%dT%H:%M:%SZ')" >> $GITHUB_OUTPUT
 
       - name: Build and push Docker image
+        id: build
         uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
         with:
           context: .
@@ -89,7 +90,7 @@ jobs:
           outputs: type=image,name=${{ env.REGISTRY }}/${{ env.IMAGE_NAME }},annotation-index.org.opencontainers.image.description=torrBotGo - Telegram bot for torrent management
 
       - name: Generate artifact attestation
-        if: github.event_name != 'pull_request'
+        if: github.event_name != 'pull_request' && steps.build.outputs.digest != ''
         uses: actions/attest-build-provenance@v1
         with:
           subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}