Filename with allow_none=False doesn't throw a warning during usage.

[micahjohnson150]

• inicheck version: 0.9.1
• Python version: 3.8
• Operating System: Ubuntu

Description

Made the following core config entry

text_file:
type=filename
default=None, 
allow_none=False

When the user doesn't specify a filename in the config, there is no warning message and it should. While this is kind of an unlikely usage it does suggest a lack of logic in the checker validity functions and IMO is technically a bug.