Use Awaited type to avoid Promise<Promise<T>>

[urbanfly]

When debouncing a Promise-returning function, the returned function has a type of Promise<Promise<T>> which is not accurate - see https://github.com/microsoft/TypeScript/issues/27711

In TypeScript 4.5, a new Awaited<T> type was introduced to solve this problem.

• docs
• release notes

This PR simply wraps the ReturnType<F> with Awaited<...> in order to get an accurate return type for the created function.

Several packages were updated:

• Typescript bumped to 4.5 in order to access this type
• microbundle in order to build
• jest / ts-jest in order to test with this type
• tsd in order to validate the types