build(deps): 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/linux.yml

@@ -67,7 +67,7 @@ jobs:
           go test -timeout 20m -v -race -cover -tags=debug -failfast -coverpkg=$(cat pkgs.txt) -coverprofile=./coverage-ci/headers.out -covermode=atomic ./...
 
       - name: Archive code coverage results
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: coverage
           path: ./tests/coverage-ci/headers.out