Why this tool force me use spaces instead of tab.

[Aerijo]

Because this package is specifically meant to enforce PEP8 style. If you don't want to follow this, turn off the package.

[masterl]

Well, to be fair PEP8 says:

Tabs or Spaces? Spaces are the preferred indentation method.

Tabs should be used solely to remain consistent with code that is already indented with tabs.

It says preferred, not mandatory. And also says that code that already uses tabs, can still use tab.