[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

@@ -143,7 +143,7 @@ jobs:
             fi
           fi
         if: matrix.kind == 'conda' || matrix.kind == 'mamba'
-      - uses: mamba-org/setup-micromamba@v2
+      - uses: mamba-org/setup-micromamba@v3
         with:
           environment-file: ${{ env.CONDA_ENV }}
           environment-name: mne
@@ -182,7 +182,7 @@ jobs:
           path: ~/mne_data
       - run: bash ./tools/github_actions_download.sh
       - run: bash ./tools/github_actions_test.sh  # for some reason on macOS we need to run "bash X" in order for a failed test run to show up
-      - uses: codecov/codecov-action@v5
+      - uses: codecov/codecov-action@v6
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
         if: success() || failure()