Fix uses of super() in the codebase

Fix #3165, we don’t need to use the long form to get the superobject in
our supported python versions.

slixmpp/exceptions.py

@@ -77,7 +77,7 @@ class IqTimeout(XMPPError):
     """
 
     def __init__(self, iq):
-        super(IqTimeout, self).__init__(
+        super().__init__(
                 condition='remote-server-timeout',
                 etype='cancel')
 
@@ -94,7 +94,7 @@ class IqError(XMPPError):
     """
 
     def __init__(self, iq):
-        super(IqError, self).__init__(
+        super().__init__(
                 condition=iq['error']['condition'],
                 text=iq['error']['text'],
                 etype=iq['error']['type'])

slixmpp/plugins/base.py

@@ -308,7 +308,7 @@ class BasePlugin(object):
         if key in self.default_config:
             self.config[key] = value
         else:
-            super(BasePlugin, self).__setattr__(key, value)
+            super().__setattr__(key, value)
 
     def _init(self):
         """Initialize plugin state, such as registering event handlers.

slixmpp/plugins/xep_0054/stanza.py

@@ -127,7 +127,7 @@ class Telephone(ElementBase):
                            'ISDN', 'PCS', 'PREF'])
 
     def setup(self, xml=None):
-        super(Telephone, self).setup(xml=xml)
+        super().setup(xml=xml)
         ## this blanks out numbers received from server
         ##self._set_sub_text('NUMBER', '', keep=True)