Replace deprecated inspect.getargspec

inspect.getargspec was deprecated since Python 3.0 and
inspect.getfullargspec is its replacement with correct handling of
function annotations and keyword-only parameters[1].

[1] https://docs.python.org/3/library/inspect.html#inspect.getargspec

Change-Id: Id91cd6dd61a0c1513e9c1bfa5672a156339f1d98

manilaclient/common/cliutils.py

@@ -55,7 +55,7 @@ def validate_args(fn, *args, **kwargs):
     :param arg: the positional arguments supplied
     :param kwargs: the keyword arguments supplied
     """
-    argspec = inspect.getargspec(fn)
+    argspec = inspect.getfullargspec(fn)
 
     num_defaults = len(argspec.defaults or [])
     required_args = argspec.args[:len(argspec.args) - num_defaults]