Bump actions/checkout from 2.3.4 to 2.4.0

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.3.4 to 2.4.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2.3.4...v2.4.0)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

.github/workflows/check-cs.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
     - name: Checkout code
-      uses: actions/checkout@v2.3.4
+      uses: actions/checkout@v2.4.0
 
     - name: Setup PHP
       uses: shivammathur/setup-php@v2

.github/workflows/promote-tag.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout code
-      uses: actions/checkout@v2.3.4
+      uses: actions/checkout@v2.4.0
       with:
         ref: ${{ github.ref }}
     - name: Pick Release Version from git tag

.github/workflows/run-tests.yml

@@ -43,7 +43,7 @@ jobs:
 
     steps:
     - name: Checkout code
-      uses: actions/checkout@v2.3.4
+      uses: actions/checkout@v2.4.0
 
     - name: Setup PHP
       uses: shivammathur/setup-php@v2