First of all, thank you for considering to contribute here!
Then, there's probably not much to do pull-request-wise here. These colorschemes are mine and I develop them on my own with my own thoughts, though if you want to fix something on an existing colorscheme, consider opening an issue first. Maybe we can get it sorted out in another way.
Feel free to open an issue if you encounter any installation issues, think that a colorscheme could be more colorblind-safe or could be enhanced otherwise.
Though this is not a Rust project, Rust's code of conduct applies here.