Remove TypeScript as an explicit peer dependency.

[Eyas]

This is one potential fix to #180 that allows schema-dts to continue to be used with import and any/no bundlers without increasing bundle size.

It is also possible to address #180 by simply asking users to save schema-dts as a dev dependency. This is generally more correct for typings, but runs the risk of leaving dangling imports to nonexistent "schema-dts" js.