fix: add validation for empty changelog before release upload

Ensure changelog is not empty before creating RC release to avoid
'size must be greater than or equal to 1' error from GitHub API.

Signed-off-by: Gerald Morrison (SAP) <gerald.morrison@sap.com>
On-behalf-of: Gerald Morrison (SAP) <gerald.morrison@sap.com>

Author: morrison-sap

.github/workflows/cli-release.yml

@@ -114,8 +114,12 @@ jobs:
       contents: write
     steps:
       - name: Decode changelog to file
+        env:
+          CHANGELOG_B64: ${{ needs.prepare.outputs.changelog_b64 }}
         run: |
-          echo "${{ needs.prepare.outputs.changelog_b64 }}" | base64 --decode > "${{ runner.temp }}/CHANGELOG.md"
+          [ -n "$CHANGELOG_B64" ] && echo "$CHANGELOG_B64" | base64 --decode > "${{ runner.temp }}/CHANGELOG.md" || true
+          # Ensure file exists and is not empty
+          [ -s "${{ runner.temp }}/CHANGELOG.md" ] || echo "Release notes not available." > "${{ runner.temp }}/CHANGELOG.md"
 
       - name: Download CLI artifacts
         uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7