Specify Python version requirements

[magicsquares137]

There is some backwards compatibility issues with versions of python prior to 3.10; namely with the typing. Use of the | operator in lines like:
def read_json_file(file_path: str | TextIO, encoding: str = "utf-8") -> dict:

doesn't work, in this case you need something like:
def read_json_file(file_path: Union[str, TextIO], encoding: str = "utf-8") -> dict:

Could either specify older versions aren't supported, or make edits to support them with the Union operator