Bump virtualenv from 20.7.1 to 20.7.2 in /.github/workflows

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.7.1 to 20.7.2.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.7.1...20.7.2)

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

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

Author: dependabot[bot]

.github/workflows/constraints.txt

@@ -2,4 +2,4 @@ pip==21.2.3
 nox==2021.6.12
 nox-poetry==0.8.6
 poetry==1.1.7
-virtualenv==20.7.1
+virtualenv==20.7.2