Bump to actions/checkout@v3

Author: FelixHerrmann

.github/workflows/update.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set name in local git-config
       run: git config --local user.name "runner"
     - name: Run update script