Bump actions/checkout from 4 to 5 (notepad-plus-plus#941)

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 5.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v5)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/CI_build.yml

@@ -19,7 +19,7 @@ jobs:
 
     steps:
     - name: Checkout repo
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
 
     - name: Install python modules
       working-directory: .