Lint modified files only with Super-Linter

https://github.com/github/super-linter#standard-image

Author: jbampton

.github/workflows/linter.yml

@@ -17,7 +17,9 @@
 
 name: Lint Code Base
 
-on: [pull_request]
+on:
+  pull_request:
+    branches: [main]
 
 permissions:
   contents: read
@@ -34,5 +36,7 @@ jobs:
       - name: SuperLinter
         uses: github/super-linter@v4
         env:
-          VALIDATE_PYTHON_FLAKE8: true
+          VALIDATE_ALL_CODEBASE: false
+          DEFAULT_BRANCH: main
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          VALIDATE_PYTHON_FLAKE8: true