Bump tox from 3.14.1 to 3.24.5 (#44)

Author: dependabot[bot]

requirements-dev.txt

@@ -3,7 +3,7 @@ click==8.0.3
 coverage==4.5.4
 flake8==3.7.9
 mypy==0.750
-tox==3.14.1
+tox==3.24.5
 twine==3.1.1
 ufmt==1.1
 usort==0.6.3