github: update actions' checkout to v3

addresses this annotation:
Node.js 12 actions are deprecated. Please update the following actions
to use Node.js 16: actions/checkout@v2. For more information see:
https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/.

.github/workflows/codeql-analysis.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
       with:
         # We must fetch at least the immediate parents so that if this is
         # a pull request then we can checkout the head.

.github/workflows/coding-style-pr.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - run: git fetch --depth=1 origin ${{ github.event.pull_request.base.sha }}
     - uses: yshui/git-clang-format-lint@v1.14
       with:

.github/workflows/coding-style.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
       with:
         fetch-depth: 2
     - uses: yshui/git-clang-format-lint@v1.14