Bump actions/checkout from 2 to 3

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 3.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v3)

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

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

.github/workflows/phpcs.yml

@@ -8,7 +8,7 @@ jobs:
       runs-on: ubuntu-latest
       steps:
         - name: Checkout
-          uses: actions/checkout@v2
+          uses: actions/checkout@v3
 
         - name: Setup PHP
           uses: shivammathur/setup-php@v2

.github/workflows/push-asset-readme-update.yml.yml

@@ -8,7 +8,7 @@ jobs:
     name: Push to master
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v3
     - name: WordPress.org plugin asset/readme update
       uses: 10up/action-wordpress-plugin-asset-update@stable
       env:

.github/workflows/push-to-deploy.yml

@@ -8,7 +8,7 @@ jobs:
     name: New tag
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v3
     - name: WordPress Plugin Deploy
       uses: 10up/action-wordpress-plugin-deploy@master
       env: