text: Title: add max number to format code using black in makefile
  Body: make format command are be caused error:
  
  `Error: Invalid value for '-l' / '--line-length': . is not a valid integer`
  
  Please, add max number after -l command in Makefile.
  
  https://github.com/scanapi/scanapi/blob/459b3c7e487a5057bec5a2f9a8e7c910b7663e9e/Makefile#L10