build(deps-dev): bump virtualenv from 20.26.5 to 20.26.6

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] <[email protected]>

Author: dependabot[bot]

requirements-dev.txt

@@ -18,7 +18,7 @@ charset-normalizer==3.3.2
     # via requests
 codespell==2.2.6
     # via -r requirements-dev.in
-coverage==7.6.1
+coverage[toml]==7.6.1
     # via
     #   -r requirements-dev.in
     #   pytest-cov
@@ -139,7 +139,7 @@ urllib3==2.2.3
     # via requests
 vcrpy==6.0.1
     # via pytest-recording
-virtualenv==20.26.5
+virtualenv==20.26.6
     # via
     #   -r requirements-dev.in
     #   asv