support python 3.12 type alias syntax

[DetachHead]

python 3.12 introduced new syntax for type aliases:

type Foo = int

this is currently highlighted incorrectly:

(the type keyword should be blue and the Foo name should be green)

related: #262

[DetachHead]

as a workaround, i've fixed this with semantic highlighting in basedpyright:

though i'm not sure how to make it blue (or if it even should be blue). DetachHead/basedpyright#147

[asottile]

I took a hacky stab at this in #270