Bump actions/checkout from 2.4.0 to 3

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.4.0 to 3.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2.4.0...v3)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/docker-build.yml

@@ -6,7 +6,7 @@ jobs:
     if: '!github.event.deleted'
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2.4.0
+    - uses: actions/checkout@v3
     - name: Docker build
       run: docker build --tag github-security-jira:latest .
     - name: Run in Docker

.github/workflows/pull_request.yml

@@ -5,7 +5,7 @@ jobs:
     name: Codestyle
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2.4.0
+    - uses: actions/checkout@v3
     - name: Setup PHP, with composer and extensions
       uses: shivammathur/setup-php@master
       with:
@@ -27,7 +27,7 @@ jobs:
     name: Static Code Analysis
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2.4.0
+    - uses: actions/checkout@v3
     - name: Setup PHP, with composer and extensions
       uses: shivammathur/setup-php@master
       with: