Add pytest for color module

[mdsanima]

This is a dev testing for specific functions and modules:

• Add pytest for _get_default_color_number functions in color module #39
• Add pytest for _set_normal_color_syntax functions in color module #40
• Add pytest for color_syntax functions in color module #41
• Add pytest for csynx aliases functions in color module #54
• Add pytest for color_print functions in color module #42
• Add pytest for cprint aliases functions in color module #55
• Add pytest for color_showcase functions in color module #43
• Add pytest for cshow aliases functions in color module #56