Bump virtualenv from 20.27.1 to 20.28.0

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.27.1 to 20.28.0.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.27.1...20.28.0)

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

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

requirements.txt

@@ -6,4 +6,4 @@ nodeenv==1.9.1
 platformdirs==4.3.6
 pre-commit==4.0.1
 PyYAML==6.0.2
-virtualenv==20.27.1
+virtualenv==20.28.0