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/release_validation.yaml

@@ -12,7 +12,7 @@ jobs:
     name: Pre-built GUI Validation
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
         with:
           submodules: recursive
 
@@ -49,7 +49,7 @@ jobs:
 
     steps:
       ### Check the version number in the code matches the tag number
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Retrieve the version number(s)
         run: |