github CI: use actions/checkout@v3

should fix the node12 deprecation warning.

.github/workflows/ci.yml

@@ -35,7 +35,7 @@ jobs:
     timeout-minutes: 10
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python
       uses: actions/setup-python@v2
       with:
@@ -77,7 +77,7 @@ jobs:
     timeout-minutes: 40
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
       with:
         # just fetching 1 commit is not enough for setuptools-scm, so we fetch all
         fetch-depth: 0

.github/workflows/codeql-analysis.yml

@@ -29,7 +29,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
       with:
         # just fetching 1 commit is not enough for setuptools-scm, so we fetch all
         fetch-depth: 0