Add very minimal linting

[itamarst]

Doesn't lint eventlet/green/ and has a very restricted set of lints, but better than nothing.

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (8d781c2) 55% compared to head (dd4c333) 56%.

Files	Patch %	Lines
eventlet/zipkin/api.py	0%	2 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #894    +/-   ##
======================================
  Coverage      55%    56%            
======================================
  Files          90     89     -1     
  Lines        9880   9717   -163     
  Branches     1832   1810    -22     
======================================
- Hits         5460   5457     -3     
+ Misses       4045   3885   -160     
  Partials      375    375            

Flag	Coverage Δ
ipv6	23% <0%> (+<1%)	⬆️
py310asyncio	53% <33%> (+<1%)	⬆️
py310epolls	53% <33%> (+<1%)	⬆️
py310poll	53% <33%> (+<1%)	⬆️
py310selects	53% <33%> (+<1%)	⬆️
py311asyncio	53% <33%> (+<1%)	⬆️
py311epolls	53% <33%> (+<1%)	⬆️
py312asyncio	50% <33%> (+<1%)	⬆️
py312epolls	51% <33%> (+<1%)	⬆️
py37asyncio	50% <33%> (+<1%)	⬆️
py37epolls	51% <33%> (+<1%)	⬆️
py38asyncio	51% <33%> (?)
py38epolls	53% <33%> (+<1%)	⬆️
py38openssl	52% <33%> (+<1%)	⬆️
py38poll	53% <33%> (+<1%)	⬆️
py38selects	53% <33%> (+<1%)	⬆️
py39asyncio	51% <33%> (+<1%)	⬆️
py39dnspython1	51% <33%> (+<1%)	⬆️
py39epolls	53% <33%> (+<1%)	⬆️
py39poll	53% <33%> (+<1%)	⬆️
py39selects	53% <33%> (+<1%)	⬆️

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[4383]

Thanks for this patch, I think some parts needs changes, see my inline comments.