dependency: bump pelican from 4.8.0 to 4.9.1

Bumps [pelican](https://github.com/getpelican/pelican) from 4.8.0 to 4.9.1.
- [Release notes](https://github.com/getpelican/pelican/releases)
- [Changelog](https://github.com/getpelican/pelican/blob/master/docs/changelog.rst)
- [Commits](getpelican/pelican@4.8.0...4.9.1)

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

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