Default floating point bands to nodata=nan when writing COGs.

[SpacemanPaul]

Reason for this pull request

Issue #1595

Proposed changes

• Always write nodata=nan to COGs for all floating point bands (unless another nodata value is explicitly set) and test.
• Update tests to pass with numpy 2.x and numpy 1.x

• Pin moto<5 (Moto API has changed slightly in v5 and several tests will need to be rewritten to support).

  • [x] Closes #1595
  • [x] Tests added / passed
  • [x] Fully documented, including docs/about/whats_new.rst for all changes

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📚 Documentation preview 📚: https://datacube-core--1602.org.readthedocs.build/en/1602/

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 91.78%. Comparing base (8b46c22) to head (783124f).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #1602 +/- ## ======================================== Coverage 91.78% 91.78% ======================================== Files 132 132 Lines 14637 14640 +3 ======================================== + Hits 13434 13437 +3 Misses 1203 1203 ```

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