github-actions(deps): bump actions/checkout from 2 to 2.3.4

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](actions/checkout@v2...v2.3.4)

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

Author: dependabot[bot]

.github/workflows/composer-normalize.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Git checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.3.4
 
       - name: Validate Composer configuration
         run: composer validate --strict

.github/workflows/markdown-normalize.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Git checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.3.4
 
       - name: Prettify markdown
         uses: creyD/prettier_action@v3.3