cmake: drop FindGuile.cmake

[pinotree]

It seems it is actually not used, as guile is currently searched with

pkg_check_modules(Guile guile-2.2)

since commit 026f2fe4bf7c4a2b62b670d76f6488929e1cded6 -- hence, drop this module.

[codecov-commenter]

Codecov Report

Merging #268 (5612ec8) into master (b60403c) will not change coverage. The diff coverage is n/a.

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@@           Coverage Diff           @@
##           master     #268   +/-   ##
=======================================
  Coverage   90.53%   90.53%           
=======================================
  Files         119      119           
  Lines       12144    12144           
=======================================
  Hits        10994    10994           
  Misses       1150     1150           

[arximboldi]

Great!