Bump ipykernel from 6.15.2 to 6.28.0

Bumps [ipykernel](https://github.com/ipython/ipykernel) from 6.15.2 to 6.28.0.
- [Release notes](https://github.com/ipython/ipykernel/releases)
- [Changelog](https://github.com/ipython/ipykernel/blob/main/CHANGELOG.md)
- [Commits](ipython/ipykernel@v6.15.2...v6.28.0)

---
updated-dependencies:
- dependency-name: ipykernel
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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