build: remove cython stuff

[tlambert03]

closes #65

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (185fab8) 100.00% compared to head (b0c20bd) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #66   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          522       521    -1     
=========================================
- Hits           522       521    -1     

Impacted Files	Coverage Δ
src/in_n_out/_util.py	100.00% <100.00%> (ø)

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[codspeed-hq]

CodSpeed Performance Report

Merging #66 will degrade performances by 15.73%

_{Comparing tlambert03:remove-cython (b0c20bd) with main (185fab8)}

Summary

❌ 2 (👁 2) regressions
✅ 3 untouched benchmarks

Benchmarks breakdown

	Benchmark	main	tlambert03:remove-cython	Change
👁	test_time_run_process	179.6 µs	213.1 µs	-15.73%
👁	test_time_run_inject_and_process	479 µs	568.2 µs	-15.7%