Remove some Python 2 compatibility code. (#6624)

python/ray/tune/function_runner.py

@@ -7,7 +7,6 @@ import time
 import inspect
 import threading
 import traceback
-import sys
 from six.moves import queue
 
 from ray.tune import track
@@ -249,10 +248,7 @@ def wrap_function(train_func):
 
     use_track = False
     try:
-        if sys.version_info >= (3, 3):
-            func_args = inspect.getfullargspec(train_func).args
-        else:
-            func_args = inspect.getargspec(train_func).args
+        func_args = inspect.getfullargspec(train_func).args
         use_track = ("reporter" not in func_args and len(func_args) == 1)
         if use_track:
             logger.info("tune.track signature detected.")