ENH: Add `scipy.special._ufuncs._iv_ratio` #14385

Job	Run time
Get commit message / Check for skips	6s
Oldest GCC & pydata/sparse, fast, py3.10/npMin, pip+pytest	19m 18s
Python-debug & ATLAS & sdist+wheel, fast, py3.10/npMin, pip+pytest	26m 8s
Install into venv, cluster only, pyAny/npAny, pip+cluster.test()	17m 55s
mypy (py3.10) & dev deps (py3.12), fast, dev.py (3.10, false)	18m 27s
mypy (py3.10) & dev deps (py3.12), fast, dev.py (3.12, false)	18m 45s
32-bit, fast, py3.10/npMin, dev.py	28m 22s
Prerelease deps & coverage report, full, py3.10/npMin & py3.11/npPre, dev.py (3.10)	28m 43s
Prerelease deps & coverage report, full, py3.10/npMin & py3.11/npPre, dev.py (3.11)	28m 27s
	3h 6m 11s

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