Remove redundant README generation

[zakame]

We already have a README.md so this is unnecessary, and the test for
this breaks the ability to install this dist directly from git.

[codecov-io]

Codecov Report

Merging #28 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #28   +/-   ##
=======================================
  Coverage   96.15%   96.15%           
=======================================
  Files           2        2           
  Lines         104      104           
  Branches       27       27           
=======================================
  Hits          100      100           
  Partials        4        4

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