test: add benchmark for fits

[beckermr]

This adds a benchmark for the fits WCS inversion code.

[codspeed-hq]

CodSpeed Performance Report

Merging #137 will not alter performance

_{Comparing fits-bench (dbdde18) with main (ba64136)}

Summary

✅ 25 untouched benchmarks
🆕 2 new benchmarks

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
🆕	test_benchmark_invert_ab_noraise[compile]	N/A	479 ms	N/A
🆕	test_benchmark_invert_ab_noraise[run]	N/A	752.6 µs	N/A