Drop six use for binary/string type identification

With Python 3.6 being the minimum supported version, dropping six here
and utilising 3.x type identifiers.

contrib/runners/winrm_runner/winrm_runner/winrm_base.py

@@ -18,7 +18,6 @@
 import base64
 import os
 import re
-import six
 import time
 
 from base64 import b64encode
@@ -257,10 +256,10 @@ def _translate_response(self, response):
         }
 
         # Ensure stdout and stderr is always a string
-        if isinstance(result["stdout"], six.binary_type):
+        if isinstance(result["stdout"], bytes):
             result["stdout"] = result["stdout"].decode("utf-8")
 
-        if isinstance(result["stderr"], six.binary_type):
+        if isinstance(result["stderr"], bytes):
             result["stderr"] = result["stderr"].decode("utf-8")
 
         # automatically convert result stdout/stderr from JSON strings to
@@ -316,7 +315,7 @@ def _upload(self, src_path_or_data, dst_path):
 
     def _upload_chunk(self, dst_path, src_data):
         # adapted from https://github.com/diyan/pywinrm/issues/18
-        if not isinstance(src_data, six.binary_type):
+        if not isinstance(src_data, bytes):
             src_data = src_data.encode("utf-8")
 
         ps = """$filePath = "{dst_path}"
@@ -446,7 +445,7 @@ def _param_to_ps(self, param):
         ps_str = ""
         if param is None:
             ps_str = "$null"
-        elif isinstance(param, six.string_types):
+        elif isinstance(param, str):
             ps_str = '"' + self._multireplace(param, PS_ESCAPE_SEQUENCES) + '"'
         elif isinstance(param, bool):
             ps_str = "$true" if param else "$false"
@@ -459,7 +458,7 @@ def _param_to_ps(self, param):
             ps_str += "; ".join(
                 [
                     (self._param_to_ps(k) + " = " + self._param_to_ps(v))
-                    for k, v in six.iteritems(param)
+                    for k, v in param.items()
                 ]
             )
             ps_str += "}"
@@ -473,7 +472,7 @@ def _transform_params_to_ps(self, positional_args, named_args):
                 positional_args[i] = self._param_to_ps(arg)
 
         if named_args:
-            for key, value in six.iteritems(named_args):
+            for key, value in named_args.items():
                 named_args[key] = self._param_to_ps(value)
 
         return positional_args, named_args
@@ -487,7 +486,7 @@ def create_ps_params_string(self, positional_args, named_args):
         ps_params_str = ""
         if named_args:
             ps_params_str += " ".join(
-                [(k + " " + v) for k, v in six.iteritems(named_args)]
+                [(k + " " + v) for k, v in named_args.items()]
             )
             ps_params_str += " "
         if positional_args: