[dependabot]: Bump the actions group with 2 updates

Bumps the actions group with 2 updates: [mamba-org/setup-micromamba](https://github.com/mamba-org/setup-micromamba) and [codecov/codecov-action](https://github.com/codecov/codecov-action).


Updates `mamba-org/setup-micromamba` from 2 to 3
- [Release notes](https://github.com/mamba-org/setup-micromamba/releases)
- [Commits](mamba-org/setup-micromamba@v2...v3)

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: mamba-org/setup-micromamba
  dependency-version: '3'
  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/tests.yml

@@ -34,7 +34,7 @@ jobs:
         with:
           python-version: ${{ matrix.python }}
         if: ${{ matrix.kind == 'pip' }}
-      - uses: mamba-org/setup-micromamba@v2
+      - uses: mamba-org/setup-micromamba@v3
         with:
           environment-file: environment.yml
           create-args: python=${{ matrix.python }}
@@ -65,7 +65,7 @@ jobs:
           key: ${{ env.TESTING_VERSION }}
           path: ~/mne_data
       - run: pytest -vv mne_realtime
-      - uses: codecov/codecov-action@v5
+      - uses: codecov/codecov-action@v6
         if: success() || failure()
         with:
           token: ${{ secrets.CODECOV_TOKEN }}