Checkout PR's code when event is pull request target

.github/workflows/codespell.yml

@@ -3,7 +3,7 @@ name: codespell
 on:
   push:
     branches:
-      - "*"
+      - master
 
   pull_request_target:
     branches:
@@ -15,16 +15,24 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
+        if: github.event_name != 'pull_request_target'
+
+      - name: Checkout pull/${{ github.event.number }}
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha }}
+        if: github.event_name == 'pull_request_target'
 
       - name: Setup micromamba
         uses: mamba-org/setup-micromamba@v1
         with:
-          environment-name: codespell-env
+          environment-name: fetch-env
           create-args: >-
             python
 
       - name: Install Codespell
-        run: pip install codespell
+        run: pip install codespell==1.10.0
 
       - name: Run codespell
         run: |