Add io-bii colormap

[pjhartzell]

Description

Adds a continuous colormap for the Impact Observatory Biodiversity Intactness Index (io-bii) dataset modeled after the UN Biodiversity Intactness Index colormap. The colormap is intended for use with the io-bii data transformed as 0.97*(data**3.84) and rescaled to [0, 1]. This results in a logarithmic colormap that focuses on intactness index values in the 0.6 to 0.95 range to better distinguish land areas that are close to the critical 0.9 index value.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Item tile preview endpoint

I imported the io-bii Collection and a few Items into a local pgstac database and used the tile preview endpoint to render an image with the proposed colormap:

legend colormap endpoint

The legend endpoint also renders the colorbar correctly:

Checklist:

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• I have performed a self-review
• Changelog has been updated
• Documentation has been updated
• Unit tests pass locally (./scripts/test)
• Code is linted and styled (./scripts/format)

[mmcfarland]

Looks good!

[pjhartzell]

@mmcfarland Could you merge the PR? Thanks!