Bump virtualenv from 20.24.5 to 20.26.6 (#155)

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.24.5 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@20.24.5...20.26.6)

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

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

Author: dependabot[bot]

requirements.dev.txt

@@ -137,7 +137,7 @@ tqdm==4.66.3
 types-python-dateutil==2.8.19.14
 tzdata==2023.3
 uri-template==1.3.0
-virtualenv==20.24.5
+virtualenv==20.26.6
 wcwidth==0.2.8
 webcolors==1.13
 webencodings==0.5.1