Bump actions/upload-artifact from 6 to 7

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 6 to 7.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v6...v7)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/cargo-test.yml

@@ -30,7 +30,7 @@ jobs:
           cargo test --verbose --no-fail-fast
 
       # Upload regression test results for analysis
-      - uses: actions/upload-artifact@v6
+      - uses: actions/upload-artifact@v7
         if: "!cancelled()"
         with:
           name: muse2_test_results_${{ matrix.os }}

.github/workflows/release.yml

@@ -48,7 +48,7 @@ jobs:
           cp target/release/muse2${{ matrix.exe_suffix }} muse2
           cp LICENSE muse2/LICENCE.txt
           cp assets/readme/readme_${{ matrix.osname }}.txt muse2/README.txt
-      - uses: actions/upload-artifact@v6
+      - uses: actions/upload-artifact@v7
         if: ${{ github.event_name != 'release' }}
         with:
           name: muse2_${{ matrix.osname }}