build(deps): bump actions/upload-artifact from 2 to 4

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 2 to 4.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](https://github.com/actions/upload-artifact/compare/v2...v4)

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

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

.github/workflows/code_coverage.yml

@@ -51,7 +51,7 @@ jobs:
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
       - name: Upload artifact
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: coverage-report
           path: coverage-report.html

.github/workflows/nightly_docs.yml

@@ -22,7 +22,7 @@ jobs:
         env:
           RUSTDOCFLAGS: '--cfg docsrs -Dwarnings'
       - name: Upload artifact
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: built-docs
           path: ./target/doc/*