Fix _imports_.py generation

[T4rk1n]

The generation for _imports_.py made a strange indentation for the __all__ key. This fix the indentation.

@nicolaskruchten @rmarren1 Please review

[rmarren1]

💃 Looks good, I got it to print

from .App import App
from .Bar import Bar
from .Foo import Foo

__all__ = [
    "App",
    "Bar",
    "Foo"
]

Not sure what is wrong with the other one... was this causing errors? Should be tested here:

dash/tests/development/test_component_loader.py

Lines 188 to 190 in 951c890

	from default_namespace.MyComponent import MyComponent \
	as MyComponent_buildtime
	from default_namespace.A import A as A_buildtime

[T4rk1n]

I don't know what caused the errors, it's tested on the boilerplate and it was generating right but when I went to dcc it failed the tests with indentation before the __all__.