Bump virtualenv from 20.14.1 to 20.16.5 in /.github/workflows (#55)

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.14.1 to 20.16.5.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.14.1...20.16.5)

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

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/constraints.txt

@@ -2,4 +2,4 @@ pip==22.1.2
 nox==2022.1.7
 nox-poetry==1.0.1
 poetry==1.1.13
-virtualenv==20.14.1
+virtualenv==20.16.5