Bump virtualenv from 20.0.6 to 20.0.21

dependabot-preview[bot] · web-flow · commit f31e6a8c79b1 · 2020-05-21T07:39:10.000Z
Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.0.6 to 20.0.21. - [Release notes](https://github.com/pypa/virtualenv/releases) - [Changelog](https://github.com/pypa/virtualenv/blob/master/docs/changelog.rst) - [Commits](pypa/virtualenv@20.0.6...20.0.21) Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
diff --git a/requirements-test.txt b/requirements-test.txt
@@ -35,5 +35,5 @@ scandir==1.10.0
 toml==0.10.0
 typing==3.7.4.1
 u-msgpack-python==2.5.2
-virtualenv==20.0.6
+virtualenv==20.0.21
 zipp==1.2.0
