Bump tox from 3.27.0 to 3.27.1

Bumps [tox](https://github.com/tox-dev/tox) from 3.27.0 to 3.27.1.
- [Release notes](https://github.com/tox-dev/tox/releases)
- [Changelog](https://github.com/tox-dev/tox/blob/master/docs/changelog.rst)
- [Commits](tox-dev/tox@3.27.0...3.27.1)

---
updated-dependencies:
- dependency-name: tox
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

requirements_dev.txt

@@ -13,6 +13,6 @@ sphinx-rtd-theme>=0.5.0
 
 # testing
 flake8>=2.6.0
-tox==3.27.0
+tox==3.27.1
 coverage>=4.3.0
 wget>=3.2