Fix masking

[dugalh]

Fixes

• Generate full cloud/shadow masks for Sentinel-2 images missing relevant cloud data (Closes #24).
• Use -inf nodata for downloaded GeoTIFFs with float64 / float32 data types to work around 350528377.
• Pin Rasterio >=1.3 for compatibility with-inf nodata .

[codecov[bot]]

Codecov Report

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

Project coverage is 91.73%. Comparing base (1bf7cbd) to head (7fc00ed).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #25 +/- ## ========================================== + Coverage 91.69% 91.73% +0.04% ========================================== Files 13 13 Lines 1613 1622 +9 ========================================== + Hits 1479 1488 +9 Misses 134 134 ```

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