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]>

Author: dependabot[bot]

.github/workflows/backwards-compatibility.yml

@@ -8,7 +8,7 @@ jobs:
         name: "Roave BC check"
         runs-on: ubuntu-latest
         steps:
-            -   uses: actions/checkout@v2
+            -   uses: actions/checkout@v3
                 with:
                     fetch-depth: 0
 

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
                 php-versions: ['7.2', '7.3', '7.4', '8.0', '8.1']
 
         steps:
-            - uses: actions/checkout@v2
+            - uses: actions/checkout@v3
 
             - name: Setup PHP
               uses: shivammathur/setup-php@v2
@@ -33,7 +33,7 @@ jobs:
         runs-on: ubuntu-latest
 
         steps:
-            - uses: actions/checkout@v2
+            - uses: actions/checkout@v3
 
             - uses: shivammathur/setup-php@v2
               with: