Issue #28915: Replace _PyObject_CallMethodId() with
_PyObject_CallMethodIdObjArgs() in unpickle(). _PyObject_CallMethodIdObjArgs()
avoids the creation of a temporary tuple and doesn't have to parse a format
string.

Replace _PyObject_CallMethodId() with _PyObject_GetAttrId()+PyObject_Call() for
the second call since it requires to "unpack" a tuple.

Add also a check in the type of the second parameter (state): it must be a
tuple.