Ensure dtype is preserved after regridding

[stephenworsley]

Adresses #238.

[stephenworsley]

Note: this will still change the dtype if you start with integer data (by design). This does mean that the dask array also will have to be changed to better align with the underlying data in this case. This should be a seperable issue which can be addressed in its own PR.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 98.71795% with 1 line in your changes missing coverage. Please review.

Project coverage is 98.85%. Comparing base (a50b2b8) to head (b587641). Report is 16 commits behind head on main.

Files with missing lines	Patch %	Lines
esmf_regrid/schemes.py	85.71%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #239 +/- ## ========================================== - Coverage 98.85% 98.85% -0.01% ========================================== Files 36 37 +1 Lines 3855 3929 +74 ========================================== + Hits 3811 3884 +73 - Misses 44 45 +1 ```

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[github-actions[bot]]

@SciTools-incubator/esmf-regrid-devs This pull-request is stale due to a lack of activity in the last 90 days. Remove stale label or comment, otherwise this pull-request will close automatically in 7 days time.

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