Log Message:
py-tox: updated to 3.2.1

3.2.1:
Bugfixes
- --parallel--safe-build no longer cleans up its folders (distdir, distshare, log).

3.2.0:
Features
- Switch pip invocations to use the module -m pip instead of direct invocation. \ 
This could help
  avoid some of the shebang limitations.
- Ability to specify package requirements for the tox run via the tox.ini (tox \ 
section under key requires - PEP-508
style): can be used to specify both plugin requirements or build dependencies.
- Allow to run multiple tox instances in parallel by providing the
  --parallel--safe-build flag.