API: quantile with bool/boolean dtypes

[jbrockmendel]

arr = np.random.randn(1000) < 0
ser = pd.Series(arr)

ser.quantile(0.5)  # <- raises

gb = ser.groupby([1] * len(ser))
gb.quantile(0.5)  # <- does not raise

Same behavior for the nullable boolean dtypes.

This should be the same for NDFrame and GroupBy. I'm fine with either allowing or raising as long as we're consistent.

[jbrockmendel]

@mroeschke @phofl preferences here? The mismatch is a blocker in fixing GroupBy.quantile perf #51385.

[mroeschke]

Looks like Series behavior raises the same error as the numpy behavior. I'm slightly leaning to matching that behavior.

Plus if this was supported, shouldn't the result be bool/boolean (gb looks to return float)?

[phofl]

I think I'd also prefer raising

[rhshadrach]

+1 on raising.