Col.__init__ has wrong type for argument `target`

[jerch]

Bug report

What's wrong

This is the current Col type declaration:

django-stubs/django-stubs/db/models/expressions.pyi

Lines 189 to 190 in 515e382

	class Col(Expression):
	def __init__(self, alias: str, target: str, output_field: Optional[_OutputField] = ...): ...

Looking at django sources, target is meant to be a Field type, not str.

How is that should be

Make target a Field type.

[sobolevn]

PR is welcome!

[sobolevn]

Fixed in #909