Bump the actions group across 1 directory with 2 updates

Bumps the actions group with 2 updates in the /.github/workflows directory: [actions/download-artifact](https://github.com/actions/download-artifact) and [codecov/codecov-action](https://github.com/codecov/codecov-action).


Updates `actions/download-artifact` from 7 to 8
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v7...v8)

Updates `codecov/codecov-action` from 5 to 6
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/main/CHANGELOG.md)
- [Commits](codecov/codecov-action@v5...v6)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-version: '8'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
- dependency-name: codecov/codecov-action
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

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

Author: dependabot[bot]

.github/workflows/publish.yml

@@ -40,7 +40,7 @@ jobs:
       id-token: write
     steps:
       - name: Download distribution artifacts
-        uses: actions/download-artifact@v7
+        uses: actions/download-artifact@v8
         with:
           name: dist
           path: dist/

.github/workflows/tests.yml

@@ -48,7 +48,7 @@ jobs:
           pytest tests -v --cov=./zodipy --cov-report=xml:./coverage.xml --cov-report term-missing
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v5
+        uses: codecov/codecov-action@v6
         with:
           files: coverage.xml
           fail_ci_if_error: false