Add cave fish atlas :fish:

Description

What is this PR

[ ] Bug fix
[x] Addition of a new feature
[ ] Other

Why is this PR needed?

We'd like to support @RobKozol 's cavefish atlas.

What does this PR do? Adds a packaging script for the cavefish atlas.

References

Closes #259

How has this PR been tested?

Please explain how any new code has been tested, and how you have ensured that no existing functionality has changed.

Is this a breaking change?

If this PR breaks any existing functionality, please explain how and why.

Does this PR require an update to the documentation?

If any features have changed, or have been added. Please explain how the documentation has been updated (and link to the associated PR). See here for details.

Checklist:

[ ] The code has been tested locally
[ ] Tests have been added to cover all new functionality (unit & integration)
[ ] The documentation has been updated to reflect any changes
[ ] The code has been formatted with pre-commit

brainglobe / brainglobe-atlasapi