Bump actions/upload-artifact from 4 to 6

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 4 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v4...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] <support@github.com>

Author: dependabot[bot]

.github/workflows/msbuild.yml

@@ -82,13 +82,13 @@ jobs:
         test.bat
 
     - name: Upload artifact (Win32)
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         name: Ultimate-ASI-Loader-Win32
         path: dist/Win32/dll/*
 
     - name: Upload artifact (x64)
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         name: Ultimate-ASI-Loader-x64
         path: dist/x64/dll/*