chore: bump virtualenv from 20.36.1 to 21.7.13 (#333)

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.36.1 to 21.7.13.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.36.1...21.7.13)

---
updated-dependencies:
- dependency-name: virtualenv
  dependency-version: 21.7.13
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]