Remove humps dependency

[sicin]

ReactShadow has 1 dependency - humps. It uses "camelize" and "decamelizeKeys" functions. Since humps has been archived by the owner on Oct 12, 2023 it's high time to remove it as dependency. Also, it's possible to move the code for those two functions into ReactShadow without any change of behavior, while also getting rid of the dependency, because humps is under MIT license.

If there is interest in removing this dependency, I can contribute with the PR.