Bump virtualenv from 1.11.6 to 20.26.6

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 1.11.6 to 20.26.6.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@1.11.6...20.26.6)

---
updated-dependencies:
- dependency-name: virtualenv
  dependency-type: direct:production
...

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

requirements.txt

@@ -148,7 +148,7 @@ simplejson==3.6.5
 six==1.10.0
 slumber==0.6.2
 sqlparse==0.2.0
-virtualenv==1.11.6
+virtualenv==20.26.6
 wsgi-intercept==0.8.0
 wsgiref==0.1.2