Bump pipenv from 2023.9.1 to 2023.9.8 in /{{cookiecutter.project_slug}} (#646)

Bumps [pipenv](https://github.com/pypa/pipenv) from 2023.9.1 to 2023.9.8.
- [Release notes](https://github.com/pypa/pipenv/releases)
- [Changelog](https://github.com/pypa/pipenv/blob/main/CHANGELOG.md)
- [Commits](pypa/pipenv@v2023.9.1...v2023.9.8)

---
updated-dependencies:
- dependency-name: pipenv
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]