Revert "Update changelog and bump version. Ref #408."

[jaraco]

This reverts premature commit 191cf5c.

I've also removed the tag 1.12.2. Ref #408.

[codecov]

Codecov Report

Merging #413 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #413   +/-   ##
=======================================
  Coverage   78.29%   78.29%           
=======================================
  Files          14       14           
  Lines         737      737           
  Branches      106      106           
=======================================
  Hits          577      577           
- Misses        127      128    +1     
+ Partials       33       32    -1

Impacted Files	Coverage Δ
twine/__init__.py	100% <100%> (ø)	⬆️
twine/wininst.py	31.57% <0%> (ø)	⬆️

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