ENH version migrator refactor

[beckermr]

Fixing bugs and trying again

Reverts #805

Closes #802
Closes #803

[codecov]

Codecov Report

Merging #807 into master will increase coverage by 0.12%.
The diff coverage is 44%.

@@            Coverage Diff             @@
##           master     #807      +/-   ##
==========================================
+ Coverage   59.61%   59.74%   +0.12%     
==========================================
  Files          32       32              
  Lines        3202     3294      +92     
==========================================
+ Hits         1909     1968      +59     
- Misses       1293     1326      +33

Impacted Files	Coverage Δ
conda_forge_tick/auto_tick.py	0% <0%> (ø)	⬆️
tests/test_upstream_versions.py	100% <100%> (ø)	⬆️
conda_forge_tick/migrators/matplotlib_base.py	95.12% <100%> (+3.81%)	⬆️
conda_forge_tick/migrators/version.py	87.41% <100%> (+0.04%)	⬆️
conda_forge_tick/make_graph.py	38.65% <16.66%> (-1.78%)	⬇️
conda_forge_tick/migrators/core.py	75.21% <33.33%> (-0.23%)	⬇️
conda_forge_tick/update_upstream_versions.py	30.71% <42.5%> (+6.26%)	⬆️
conda_forge_tick/utils.py	60.99% <75%> (+0.16%)	⬆️

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[scopatz]

There is a lot going on here, but it generally looks good to me! Any objections to merging this?

[beckermr]

Sorry yeah this one got out of hand. :/

No objections - I reverted it a few times due to bugs