Support syntax def myfunc(arg: "float64[:,:]"):

[paugier]

I get a lot of warnings like

`WARNING: could not parse arglist ('arg: float64[:,:]'): Unable to parse Slice object`

as soon as I use Transonic / Pythran syntax in annotations, i.e. for code like:

Ac = "float64[:,:]"

def myfunc(arg: Ac):
   ...

This is a correct syntax for code annotations, so it would be nice to at least have no warning in this case.

Note that the rendered documentation is correct for such case. The problem is really the warnings.

[AA-Turner]

A PR is welcome.

A