Update actions/checkout from v2 to v3

pr-checks/checks/with-checkout-path.yml

@@ -7,7 +7,7 @@ os: [ubuntu-latest, macos-latest, windows-2019]
 steps:
   # Check out the actions repo again, but at a different location.
   # choose an arbitrary SHA so that we can later test that the commit_oid is not from main
-  - uses: actions/checkout@v2
+  - uses: actions/checkout@v3
     with:
       ref: 474bbf07f9247ffe1856c6a0f94aeeb10e7afee6
       path: x/y/z/some-path

pr-checks/sync.py

@@ -49,7 +49,7 @@ for file in os.listdir('checks'):
     steps = [
         {
             'name': 'Check out repository',
-            'uses': 'actions/checkout@v2'
+            'uses': 'actions/checkout@v3'
         },
         {
             'name': 'Prepare test',