Bump actions/checkout from 2 to 2.3.4 (#793)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 2.3.4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v2...v2.3.4)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/build.yml

@@ -14,7 +14,7 @@ jobs:
     timeout-minutes: 10
     if: "!contains(github.event.head_commit.message, 'skip ci')"
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
       - name: Set up Python
@@ -28,7 +28,7 @@ jobs:
     timeout-minutes: 30
     if: "!contains(github.event.head_commit.message, 'skip ci')"
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
       - name: Set up Python
@@ -109,7 +109,7 @@ jobs:
       PY_IGNORE_IMPORTMISMATCH: yes
       SECRETS_AVAILABLE: ${{ secrets.SECRETS_AVAILABLE }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
       - name: Set up MSYS2
@@ -186,7 +186,7 @@ jobs:
       PKG_CONFIG_PATH: /usr/local/opt/libffi/lib/pkgconfig:/usr/local/opt/python@3.8/lib/pkgconfig:${PKG_CONFIG_PATH:-}
       SECRETS_AVAILABLE: ${{ secrets.SECRETS_AVAILABLE }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
       - name: Set up Python

.github/workflows/codeql-analysis.yml

@@ -25,7 +25,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v2.3.4
       with:
         # We must fetch at least the immediate parents so that if this is
         # a pull request then we can checkout the head.