Use base ref branch for pylint

.github/workflows/pylint.yml

@@ -9,9 +9,6 @@ defaults:
 on:
   pull_request:
     branches: [master, dev]
-  schedule:
-    # run CI every day even if no PRs/merges occur
-    - cron: '0 12 * * *'
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
@@ -45,7 +42,9 @@ jobs:
         env:
           # Run linters only on new files for pylint to speed up the CI
           VALIDATE_ALL_CODEBASE: false
-          DEFAULT_BRANCH: master
+          # Compare against the base branch
+          # This is only accessible on PR
+          DEFAULT_BRANCH: ${{ github.base_ref }}
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           # Run only pylint
           VALIDATE_PYTHON: true