Bump pytest-expecter from 3.0 to 3.1

Bumps [pytest-expecter](https://github.com/jacebrowning/pytest-expecter) from 3.0 to 3.1.
- [Release notes](https://github.com/jacebrowning/pytest-expecter/releases)
- [Changelog](https://github.com/jacebrowning/pytest-expecter/blob/main/CHANGELOG.md)
- [Commits](jacebrowning/pytest-expecter@v3.0...v3.1)

---
updated-dependencies:
- dependency-name: pytest-expecter
  dependency-version: '3.1'
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]