chore(deps): bump actions/checkout from 2 to 4 (aws#783)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.

Author: dependabot[bot]

.github/workflows/clang-format.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - uses: DoozyX/[email protected]
       with:
         source: '.'

.github/workflows/osx.yml

@@ -18,20 +18,20 @@ jobs:
       - run: brew install ${{ matrix.openssl_version }}
 
       - name: Checkout PR
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           submodules: recursive
         if: ${{ github.repository == 'aws/aws-encryption-sdk-c' }}
 
       - name: Checkout PR with CI bot token
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           submodules: recursive
           token: ${{ secrets.CI_BOT_TOKEN }}
         if: ${{ github.repository == 'aws/private-aws-encryption-sdk-c-staging' }}
 
       - name: Checkout AWS C++ SDK
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           repository: "aws/aws-sdk-cpp"
           path: "aws-sdk-cpp"

.github/workflows/proof_ci.yaml

@@ -30,7 +30,7 @@ jobs:
       pull-requests: read
     steps:
       - name: Check out repository and submodules recursively
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           submodules: 'recursive'
       - name: Parse config file

.github/workflows/repo-sync.yml

@@ -9,7 +9,7 @@ jobs:
     environment: repo-sync
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - uses: repo-sync/github-sync@v2
       name: Sync repo to branch
       with: