Bump actions/upload-artifact from 5 to 6

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v5...v6)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/CI_build.yml

@@ -86,7 +86,7 @@ jobs:
             Rename-Item -Path static_html -NewName nppUserManual
 
     - name: 🎉 Store zipfile as artifact
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       with:
           name: nppUserManual
           path: ./nppUserManual/