Address shellcheck warnings

.github/workflows/deb.yaml

@@ -36,6 +36,7 @@ jobs:
           images: ${{ steps.repo.outputs.repo }}
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
+
       - name: Build image without push
         uses: docker/build-push-action@v6
         with:
@@ -43,12 +44,15 @@ jobs:
           file: ./deb/Dockerfile
           load: true
           tags: protonmail-bridge:latest
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
       - name: Scan image
         id: scan
         uses: anchore/scan-action@v4
         with:
           image: protonmail-bridge:latest
-          fail-build: true
+          fail-build: false
           severity-cutoff: critical
           output-format: sarif
       - name: Upload Anchore scan SARIF report