Update license to MIT and setutools pins

[valeriupredoi]

Description

Update license to a bogstandard MIT one identical to cf-python's, so we have uniformity across NCAS-CMS.

Before you get started

• ☝ Create an issue to discuss what you are going to do

Checklist

• This pull request has a descriptive title and labels
• This pull request has a minimal description (most was discussed in the issue, but a two-liner description is still desirable)
• Any changed dependencies have been added or removed correctly (if need be)
• All tests pass

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.00%. Comparing base (c8e7d8a) to head (f6fde1d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #301   +/-   ##
=======================================
  Coverage   86.00%   86.00%           
=======================================
  Files           7        7           
  Lines         643      643           
=======================================
  Hits          553      553           
  Misses         90       90           

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