Fix: unit tests ran twice for every push to a pull request

This revision runs tests once for a pull request and once for any push to
the main branch.

Signed-off-by: Jesse Whitehouse <jesse.whitehouse@databricks.com>

Author: Jesse Whitehouse

.github/workflows/code-quality-checks.yml

@@ -1,5 +1,11 @@
 name: Code Quality Checks
-on: [pull_request, push]
+on: 
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
 jobs:
   run-unit-tests:
     runs-on: ubuntu-latest