chore(ci): run codespell on the actual PR commit, instead of the merg…

…e one

.github/workflows/lint.yml

@@ -61,13 +61,19 @@ jobs:
     name: Run codespell
     runs-on: ubuntu-latest
     steps:
-    - name: Checkout code
+    - name: Check out the PR commit head
       uses: actions/checkout@v4
+      if: github.event_name == 'pull_request'
+      with:
+        ref: ${{ github.event.pull_request.head.sha }}
+    - name: Check out the repo
+      uses: actions/checkout@v4
+      if: github.event_name != 'pull_request'
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
         python-version: "3.x"
     - name: Install codespell
       run: pip install codespell
     - name: Run codespell
-      run: codespell
+      run: codespell