Add license information to swagger spec

[slifty]

This PR adds some license information to our swagger specification.

This means the license gets rendered on our api page:

I wasn't able to add an identifier attribute even though it is listed as a valid attribute in the specification. Our validator complained about it. Rather than debug, I think this is good enough and meets 99% of the value of including this information at all.

Resolves #853

[codecov[bot]]

Codecov Report

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

Project coverage is 88.57%. Comparing base (300465a) to head (2051e81).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1109 +/- ## ======================================= Coverage 88.57% 88.57% ======================================= Files 129 129 Lines 1725 1725 Branches 220 220 ======================================= Hits 1528 1528 Misses 182 182 Partials 15 15 ```

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