auto_var_types: Automaticall assign var_types to the attributes
In haozhu233/ezsummary: Generate Data Summary in a Tidy Format

If the user did not provide var_types, the function will preassume every variables to be quantitative variables. If a variable's type is character but either the user or the automatic step said it's a quantitative variable, the var_types attribute for that variable will be overwritten as categorical variable. At the same time, a warning message will be printed on the screen.