Fix YAML parse error: use block scalar for echo with colons

Gitea's YAML parser treats `echo "text: value"` as a mapping when
on a single `run:` line. Using block scalar (`run: |`) avoids this.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/build-sidecar-macos.yml

@@ -16,7 +16,8 @@ jobs:
       RELEASE_TAG: "${{ inputs.tag }}"
     steps:
       - name: Show tag
-        run: echo "Building for tag: ${RELEASE_TAG}"
+        run: |
+          echo "Building for tag: ${RELEASE_TAG}"
 
       - uses: actions/checkout@v4
         with: