Move from attrs to dataclasses

[hukkin]

BREAKING CHANGES

• Token.as_dict -- Moved to using a simple dataclasses.asdict call. This means that many keyword arguments are removed from the method. Output is also slightly different (see .yml test regression files in this PR).
• Token.copy -- Moved from attr.evolve to a simple copy.copy call. The stdlib copy.copy call does quite literally what the docstring of Token.copy says which is "return a shallow copy of the instance". Does attr.evolve do something extra? Is there a chance someone relies on this extra behavior? EDIT: Answering my own question: Without keyword arguments, attr.evolve seems doesn't seem to do anything that copy.copy doesn't. I don't think this is a breaking change.

[codecov]

Codecov Report

Merging #200 (388f78c) into master (32097fb) will increase coverage by 0.00%.
The diff coverage is 98.07%.

@@           Coverage Diff           @@
##           master     #200   +/-   ##
=======================================
  Coverage   96.14%   96.15%           
=======================================
  Files          61       62    +1     
  Lines        3244     3251    +7     
=======================================
+ Hits         3119     3126    +7     
  Misses        125      125           

Flag	Coverage Δ
pytests	96.15% <98.07%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
markdown_it/_compat.py	85.71% <85.71%> (ø)
markdown_it/ruler.py	89.74% <100.00%> (+0.08%)	⬆️
markdown_it/rules_inline/state_inline.py	97.91% <100.00%> (+0.02%)	⬆️
markdown_it/token.py	91.39% <100.00%> (+0.87%)	⬆️

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[chrisjsewell]

Why not just use https://docs.python.org/3/library/dataclasses.html#dataclasses.replace

[hukkin]

Oh wasn't aware such API existed.

However, since we don't use the kwargs or replace anything, I think I'd prefer copy.copy for readability. What do you think?

[chrisjsewell]

Heya @hukkin I went ahead and did this in #212, keeping outputs the same.

Didn't add the slots compat, because I was lazy. Feel free to add