ci: add type=sha tag so each build gets an immutable sha-<commit> tag

Author: matteius

.github/workflows/docker-image.yml

@@ -43,6 +43,7 @@ jobs:
             type=semver,pattern={{version}}
             type=semver,pattern={{major}}.{{minor}}
             type=raw,value=latest,enable={{is_default_branch}}
+            type=sha
 
       - name: Build and push Docker image
         uses: docker/build-push-action@v5