Bump virtualenv from 20.26.3 to 20.26.4

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.26.3 to 20.26.4.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.26.3...20.26.4)

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

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

ci-constraints-requirements.txt

@@ -265,7 +265,7 @@ urllib3==2.0.7 ; python_full_version < '3.8'
     # via requests
 urllib3==2.2.2 ; python_full_version >= '3.8'
     # via requests
-virtualenv==20.26.3
+virtualenv==20.26.4
     # via nox
 webencodings==0.5.1 ; python_full_version < '3.8'
     # via bleach