Build: Bump virtualenv from 21.5.1 to 21.7.12

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 21.5.1 to 21.7.12.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@21.5.1...21.7.12)

---
updated-dependencies:
- dependency-name: virtualenv
  dependency-version: 21.7.12
  dependency-type: indirect
...

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Author: dependabot[bot]