Bump virtualenv from 20.17.1 to 20.18.0

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.17.1 to 20.18.0.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.17.1...20.18.0)

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

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

requirements_dev.txt

@@ -36,5 +36,5 @@ requests==2.28.1; python_version >= "3.7" and python_version < "4" and (python_v
 tomli==2.0.1; python_version < "3.11" and python_version >= "3.7" and python_full_version <= "3.11.0a6" and (python_version >= "3.7" and python_full_version < "3.0.0" or python_full_version >= "3.4.0" and python_version >= "3.7")
 typing-extensions==4.4.0; python_version >= "3.7"
 urllib3==1.26.13; python_version >= "3.7" and python_full_version < "3.0.0" and python_version < "4" and (python_version >= "2.7" and python_full_version < "3.0.0" or python_full_version >= "3.4.0") or python_version >= "3.7" and python_version < "4" and (python_version >= "2.7" and python_full_version < "3.0.0" or python_full_version >= "3.4.0") and python_full_version >= "3.6.0"
-virtualenv==20.17.1; python_version >= "3.7"
+virtualenv==20.18.0; python_version >= "3.7"
 yarl==1.8.2; python_version >= "3.7"