Readd Request.get_creator method (for backward compatibility)

Request.get_creator is used by some factory bots (see comment
in issue #286).

Note: Request.get_creator is deprecated and the "creator" attribute
should be used instead.

osc/core.py

@@ -2738,6 +2738,13 @@ class Request:
             return self.actions
         return [i for i in self.actions if i.type in types]
 
+    def get_creator(self):
+        """Return the creator of the request.
+
+        This method is deprecated (use "creator" attribute instead").
+        """
+        return self.creator
+
     def to_xml(self):
         """serialize object to XML"""
         root = ET.Element('request')