Add license information to package.json

[mathiasrw]

What does this PR do?

Add MIT as license information in the package.json of bun-types

How did you verify your code works?

No code changed

Assumtions

bun-types is distributed under MIT just like the rest of the Bun project as indicated here: https://bun.sh/docs/project/licensing

Background

I use bun for bundling and testing, so I depend on bun-types. But without the license information in the package.json I get this FOSSA warning

[Electroid]

Thanks!