Bump actions/upload-artifact from 4 to 6 (#112)

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

Author: dependabot[bot]

.github/workflows/coverage.yml

@@ -23,7 +23,7 @@ jobs:
       run: dotnet dotcover test --dcXML=Configuration.xml
 
     - name: Save Report
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         name: coverage-report
         path: CoverageReport.xml

.github/workflows/release.yml

@@ -26,15 +26,15 @@ jobs:
       run: dotnet dotcover test --dcXML=Configuration.xml
 
     - name: Save DateTimeOnly Packages
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         name: packages
         path: |
           DateTimeOnly/bin/Release/*.nupkg
           DateTimeOnly/bin/Release/*.snupkg
 
     - name: Save DateTimeOnly.Json Packages
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         name: packages-json
         path: |