Bump virtualenv from 20.26.5 to 20.26.6 (#105)

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.26.5 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@20.26.5...20.26.6)

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

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

development-requirements.txt

@@ -27,5 +27,5 @@ sphinxcontrib-jsmath==1.0.1
 sphinxcontrib-qthelp==2.0.0
 sphinxcontrib-serializinghtml==2.0.0
 twine==5.1.1
-virtualenv==20.26.5
+virtualenv==20.26.6
 wheel==0.44.0