Bump virtualenv from 20.0.15 to 20.26.6

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.0.15 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@20.0.15...20.26.6)

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

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

Author: dependabot[bot]

requirements.txt

@@ -1,2 +1,2 @@
 PyYAML==5.4
-virtualenv==20.0.15
+virtualenv==20.26.6