build(deps): bump tox from 3.15.1 to 3.17.1 (#459)

Bumps [tox](https://github.com/tox-dev/tox) from 3.15.1 to 3.17.1.
- [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@3.15.1...3.17.1)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

requirements/test.txt

@@ -4,4 +4,4 @@ pytest==5.4.3             # via -r requirements/test.txt, pytest-cov, pytest-tes
 pytest-cov==2.8.1         # via -r requirements/test.txt
 pytest-runner==5.2        # via -r requirements/test.txt
 pytest-testmon==1.0.2     # via -r requirements/test.txt
-tox==3.15.1               # via -r requirements/test.txt
+tox==3.17.1               # via -r requirements/test.txt