Make doepy compatible with python<3.7

[Sigmun]

add file encoding in headers and use "".format() instead of f"" strings

[JoshuaAdrianJones]

Could you wrap this in a conditional to check for python version rather than replacing a newer more pythonic version completely?

[Sigmun]

You'd rather have 2 lines for the same function just to deal with retro-compatibility than using the same function in every cases? I think you'll increase code maintenance load.