Bump virtualenv from 20.0.34 to 20.0.35 in /.github/workflows (#625)

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.0.34 to 20.0.35.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.0.34...20.0.35)

Signed-off-by: dependabot[bot] <support@github.com>

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

Author: cjolowicz

{{cookiecutter.project_name}}/.github/workflows/constraints.txt

@@ -2,4 +2,4 @@ pip==20.2.3
 nox==2020.8.22
 nox-poetry==0.5.0
 poetry==1.1.2
-virtualenv==20.0.34
+virtualenv==20.0.35