Support class constructors

[snorkysnark]

Since types are also callable functions that return the type instance, I'd like for the following merge to be possible

class Foo:
    def __init__(self, bb: str) -> None:
        pass

@merge_args(Foo)
def run_cmd(aa: str, *args, **kwargs) -> Foo:
    return Foo(*args, **kwargs)

help(run_cmd)

Expected:

run_cmd(aa: str, bb: str) -> __main__.Foo

Error:

Traceback (most recent call last):
  File "/home/lisk/Code/ralsei/ralsei/console/./app2.py", line 9, in <module>
    @merge_args(Foo)
     ^^^^^^^^^^^^^^^
  File "/home/lisk/Code/ralsei/ralsei/__pypackages__/3.11/lib/merge_args.py", line 116, in _merge
    'co_flags': source.__code__.co_flags,
                ^^^^^^^^^^^^^^^
AttributeError: type object 'Foo' has no attribute '__code__'.