Log Message:
py-tox: updated to 3.7.0

v3.7.0:

Features
- Parallel mode added (alternative to detox which is being deprecated), for more \ 
details see :ref:parallel_mode
- Added command line shortcut -s for --skip-missing-interpreters

Deprecations (removal in next major release)
- Whitelisting of externals will be mandatory in tox 4: issue a deprecation \ 
warning as part of the already existing warning

Documentation
- Clarify explanations in examples and avoid unsupported end line comments
- Set to PULL_REQUEST_TEMPLATE.md use relative instead of absolute URLs
  Fixed PULL_REQUEST_TEMPLATE.md path for changelog/examples.rst to \ 
docs/changelog/examples.rst