Use origin/master instead of master in verify workflow

.github/workflows/verify.yml

@@ -12,7 +12,7 @@ jobs:
         fetch-depth: 0
     - name: Check `CHANGELOG.md` has changes
       run: |
-        ! git diff --exit-code master HEAD CHANGELOG.md
+        ! git diff --exit-code origin/master HEAD -- CHANGELOG.md
     - name: Check `CHANGELOG.md` has PR author
       if: ${{ github.event.pull_request.user.login != 'hecrj' }}
       run: |