Support wisp v2

[JonasGruenwald]

@ghivert hi, thanks for your work on this package, I'd love to use it with wisp 2.0 :)

[ghivert]

Hi! Thanks for your contribution! I'd like to avoid breaking compatibility with wisp 1. Could you, instead of returning wisp.Text(""), return wisp.Bytes()? That would allow to relax the dependencies of cors_builder, and Wisp requirements could be >= 1.0.0 and < 3.0.0. That way, we could make sure to not split the codebase, and let people upgrade cors_builder and wisp each at their own rhythm.

[JonasGruenwald]

@ghivert makes a lot of sense! I've made that change.

[ghivert]

Thanks! Can you please update the tests and the CHANGELOG.md?

[JonasGruenwald]

Sure! I don't think anything should change for the tests, but it appears that the Gleam version used in CI is too old, I've updated that and the changelog.

[ghivert]

Thank you!