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/pull-request.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Upload
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: Event File
           path: ${{ github.event_path }}
@@ -40,7 +40,7 @@ jobs:
         run: dotnet test -c Debug -f ${{ matrix.dotnet }}
       - name: Upload Test Results
         if: always()
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: Test Results Windows ${{ matrix.dotnet }}
           path: |
@@ -68,7 +68,7 @@ jobs:
         run: dotnet test -f ${{ matrix.dotnet }}
       - name: Upload Test Results
         if: always()
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: Test Results Ubuntu ${{ matrix.dotnet }}
           path: |