[STYLE] Improved quoting in CI-BUILD.yml (- WIP #266 -)

Changes in file .github/workflows/CI-BUILD.yml:

  * refactored `$GITHUB_OUTPUT` to `"$GITHUB_OUTPUT"`

Author: reactive-firewall

.github/workflows/CI-BUILD.yml

@@ -163,7 +163,7 @@ jobs:
       - id: check_status
         run: |
           if [[ "${{ needs.BUILD.result }}" == "success" && "${{ needs.BOOTSTRAP.result }}" == "success" ]]; then
-            echo "build_success=true" >> $GITHUB_OUTPUT
+            echo "build_success=true" >> "$GITHUB_OUTPUT"
           else
-            echo "build_success=false" >> $GITHUB_OUTPUT
+            echo "build_success=false" >> "$GITHUB_OUTPUT"
           fi