chore(deps): bump virtualenv in /.github/workflows

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.34.0 to 20.35.4.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.34.0...20.35.4)

---
updated-dependencies:
- dependency-name: virtualenv
  dependency-version: 20.35.4
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

.github/workflows/constraints.txt

@@ -1,3 +1,3 @@
 pip==25.2
 nox==2025.5.1
-virtualenv==20.34.0
+virtualenv==20.35.4