ci(build): skip commitizen on pull requests

A conventional commit can be made on merge.

Author: bcanseco

.github/workflows/build.yml

@@ -8,6 +8,7 @@ on:
 
 jobs:
   commitizen:
+    if: github.event_name == 'push' && github.ref == 'refs/heads/master'
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@master