Reprojection changes floating point precision

Hi there.

This very line:
https://github.com/astropy/reproject/blob/3bb79cdfab86da32169bbbb73e907e22ad9783aa/reproject/interpolation/core.py#L95
changes an input array with dtype=float32 to float64.

Could we replace it with a mere check (for all floating point types) instead, and raise an error in case the input isn't a float?

Start at reproject/interpolation/core.py line 95, where the issue reports that float32 input becomes float64. Inspect the surrounding dtype handling, then verify that floating-point inputs retain their precision and that non-floating input raises an error. No test file is named in the issue.

Written by the indexing model from the issue text.