Add package.json pls

[AndriyAntonenko]

In our project, we use Foundry for development, but we prefer managing dependencies with Bun as it simplifies the process. It would be great if a package.json file could be added for the Murky library. Murky is a unique library that allows us to generate Merkle trees using Solidity, and having a package.json would make it easier to integrate and manage within our existing workflow.