build(deps): bump virtualenv from 20.19.0 to 20.20.0

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.19.0 to 20.20.0.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.19.0...20.20.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements-bench.txt

@@ -1,2 +1,2 @@
 asv==0.5.1
-virtualenv==20.19.0
+virtualenv==20.20.0