Bump actions/upload-artifact from 6 to 7 (#449)

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -37,7 +37,7 @@ jobs:
       run: sbt -v compileDocumentation
     - name: Test
       run: sbt -v test
-    - uses: actions/upload-artifact@v6  # upload test results
+    - uses: actions/upload-artifact@v7  # upload test results
       if: success() || failure()        # run this step even if previous step failed
       with:
         name: 'tests-results-java-21'