ci(bluebuild): symlink podman -> docker (action needs docker CLI)

.github/workflows/build-bluebuild.yml

@@ -76,6 +76,12 @@ jobs:
             buildah \
             skopeo \
             jq
+          # blue-build/github-action shells out to `docker`; Fedora ships
+          # podman. Symlink so the action finds the CLI.
+          if ! command -v docker >/dev/null; then
+            ln -sf "$(command -v podman)" /usr/local/bin/docker
+            docker --version
+          fi
 
       - name: Install cosign binary (upstream release)
         run: |