This cleans up the GitHub actions yaml a bit and ensures that developers
are running this check locally before submitting changes. In addition,
it allows adding tests for this check. Finally, this change fixes the
tidy tests by upgrading voluptuous for Python 3.10 as well as by
reverting an inadvertent change for NixOS compatibility on one of the
dummy testing files.
Running `servo-tidy` in a virtualenv where all you've done is `pip install servo-tidy==0.3.0` doesn't actually work because of missing dependencies. PyYAML and voluptuous are required as well. I don't know anything about python package management but declaring these missing dependencies seems like an appropriate thing to do. Patch itself is untested because I don't know how, although with these dependencies installed in my virtualenv running `servo-tidy` works.
- also update requriements "pyflakes" from 0.8 to 0.8.1 due to following issue
```
Traceback (most recent call last):
File "/Users/Askeing/software/servo/python/_virtualenv/bin/servo-tidy", line 5, in <module>
from pkg_resources import load_entry_point
File "/Users/Askeing/software/servo/python/_virtualenv/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3084, in <module>
@_call_aside
File "/Users/Askeing/software/servo/python/_virtualenv/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3070, in _call_aside
f(*args, **kwargs)
File "/Users/Askeing/software/servo/python/_virtualenv/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3097, in
_initialize_master_working_set
working_set = WorkingSet._build_master()
File "/Users/Askeing/software/servo/python/_virtualenv/lib/python2.7/site-packages/pkg_resources/__init__.py", line 653, in _build_master
return cls._build_from_requirements(__requires__)
File "/Users/Askeing/software/servo/python/_virtualenv/lib/python2.7/site-packages/pkg_resources/__init__.py", line 666, in
_build_from_requirements
dists = ws.resolve(reqs, Environment())
File "/Users/Askeing/software/servo/python/_virtualenv/lib/python2.7/site-packages/pkg_resources/__init__.py", line 839, in resolve
raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'pyflakes==0.8.1' distribution was not found and is required by servo-tidy
```
