Bump nbstripout from 0.9.0 to 0.9.1

Bumps [nbstripout](https://github.com/kynan/nbstripout) from 0.9.0 to 0.9.1.
- [Release notes](https://github.com/kynan/nbstripout/releases)
- [Changelog](https://github.com/kynan/nbstripout/blob/main/CHANGELOG.md)
- [Commits](kynan/nbstripout@0.9.0...0.9.1)

---
updated-dependencies:
- dependency-name: nbstripout
  dependency-version: 0.9.1
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]