Bump virtualenv from 20.17.0 to 20.21.0

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.17.0 to 20.21.0.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.17.0...20.21.0)

---
updated-dependencies:
- dependency-name: virtualenv
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements/production.txt

@@ -17,4 +17,4 @@ pip==23.0.1
 psycopg2==2.9.5
 pytz==2022.7.1
 sentry-sdk==1.11.1
-virtualenv==20.17.0
+virtualenv==20.21.0