Bump actions/checkout from 2 to 4 (#478)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v4)

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

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

.github/workflows/lint-test.yml

@@ -7,14 +7,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - uses: pantheon-systems/validate-readme-spacing@v1
   lint:
     name: PHPCS Linting
     runs-on: ubuntu-latest
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Cache dependencies
       uses: actions/cache@v4
       with:
@@ -34,7 +34,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: WP.org Validator
         uses: pantheon-systems/[email protected]
         with:
@@ -44,7 +44,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - uses: pantheon-systems/phpcompatibility-action@dev
         with:
           paths: ${{ github.workspace }}/*.php
@@ -65,7 +65,7 @@ jobs:
         ports:
           - 6379:6379
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
         with:

.github/workflows/wordpress-plugin-deploy.yml

@@ -7,7 +7,7 @@ jobs:
   release:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: WordPress Plugin Deploy
       uses: 10up/[email protected]
       env:

.github/workflows/wporg-validator.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: WP.org Validator
         uses: pantheon-systems/[email protected]
         with: