[CI] Allow code coverage report deploy only from master

.github/workflows/unit-test.yml

@@ -38,6 +38,7 @@ jobs:
         path: extras/test/unit/lcov.report
 
     - name: Deploy to GitHub Pages
+      if: github.ref == 'refs/heads/master'
       uses: peaceiris/actions-gh-pages@v3
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}