deps(ci): 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](https://github.com/actions/upload-artifact/compare/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] <support@github.com>

.github/workflows/tests.yml

@@ -35,14 +35,14 @@ jobs:
 
       - name: Upload Unit Test Results
         if: always()
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: test-results-${{ matrix.os }}
           path: komga/build/test-results/
 
       - name: Upload Unit Test Reports
         if: always()
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: test-reports-${{ matrix.os }}
           path: komga/build/reports/tests/
@@ -69,7 +69,7 @@ jobs:
 
       - name: Upload JDK required modules
         if: steps.conveyor_compare.outcome == 'failure'
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: conveyor-required-jdk-modules
           path: ./output/required-jdk-modules.txt