build(deps-dev): bump virtualenv in the pip group

Bumps the pip group with 1 update: [virtualenv](https://github.com/pypa/virtualenv).


Updates `virtualenv` from 20.26.3 to 20.26.6
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.26.3...20.26.6)

---
updated-dependencies:
- dependency-name: virtualenv
  dependency-type: indirect
  dependency-group: pip
...

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Author: dependabot[bot]