Revert version bump check to only trigger on PRs targeting main

Author: SihaoLiu

.github/workflows/version-bump-check.yml

@@ -2,26 +2,18 @@ name: Version Bump Check
 
 on:
   pull_request:
-    branches: [main, dev]
+    branches: [main]
 
 jobs:
   version-bump-check:
     runs-on: ubuntu-latest
     steps:
-      - name: Skip for non-main targets
-        if: github.base_ref != 'main'
-        run: |
-          echo "PR targets '${{ github.base_ref }}', not 'main'. Skipping version bump check."
-          exit 0
-
       - name: Checkout PR branch
-        if: github.base_ref == 'main'
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
       - name: Check version bump
-        if: github.base_ref == 'main'
         run: |
           echo "Checking that all version numbers have been incremented..."