Version compatible inspect handling for class parameters (#299)

* Version compatible inspect handling for class parameters

`getargspec` was deprecated in Python 3.0, but finally removed in Python
3.11. For reference: Pylons/pyramid#3688

That seems like a valid amount of time.

We can do our best effort and if the user is running a Python version
that still has `getargspec` use that, but if they have `getfullargspec`
which is available in Python 3.11, we can use that.

* Update ir_generator.py

include `isclass`

stone/frontend/ir_generator.py

@@ -3,9 +3,14 @@
 from collections import defaultdict
 
 import copy
-import inspect
 import logging
 
+from inspect import isclass
+try:
+    from inspect import getfullargspec as get_args
+except ImportError:
+    from inspect import getargspec as get_args
+
 _MYPY = False
 if _MYPY:
     import typing  # noqa: F401 # pylint: disable=import-error,unused-import,useless-suppression
@@ -1074,7 +1079,7 @@ def _instantiate_data_type(self, data_type_class, data_type_args, loc):
         assert issubclass(data_type_class, DataType), \
             'Expected stone.data_type.DataType, got %r' % data_type_class
 
-        argspec = inspect.getargspec(data_type_class.__init__)  # noqa: E501 # pylint: disable=deprecated-method,useless-suppression
+        argspec = get_args(data_type_class.__init__)  # noqa: E501 # pylint: disable=deprecated-method,useless-suppression
         argspec.args.remove('self')
         num_args = len(argspec.args)
         # Unfortunately, argspec.defaults is None if there are no defaults
@@ -1154,7 +1159,7 @@ def _resolve_type(self, env, type_ref, enforce_fully_defined=False):
         if obj is Void and type_ref.nullable:
             raise InvalidSpec('Void cannot be marked nullable.',
                               *loc)
-        elif inspect.isclass(obj):
+        elif isclass(obj):
             resolved_data_type_args = self._resolve_args(env, type_ref.args)
             data_type = self._instantiate_data_type(
                 obj, resolved_data_type_args, (type_ref.lineno, type_ref.path))