Remove six dependency

Change-Id: I6b7c8bed9d7ac6427e57bb146ce95de7e8bf1934

requirements.txt

@@ -2,4 +2,3 @@ python-subunit>=0.0.18
 testtools>=0.9.30
 oslo.db>=6.0.0;python_version>='3.6'
 oslo.db==6.0.0;python_version<='3.5'
-six

stackviz/parser/log_node.py

@@ -12,8 +12,6 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import six
-
 from datetime import datetime
 from datetime import timedelta
 
@@ -147,7 +145,7 @@ class LogNode(object):
                 else:
                     if value is None:
                         p.text(tc.Blue)
-                    elif isinstance(value, six.string_types):
+                    elif isinstance(value, str):
                         p.text(tc.Red)
                     elif isinstance(value, Number):
                         p.text(tc.DarkGray)

stackviz/parser/tempest_subunit.py

@@ -15,7 +15,6 @@
 import os
 import re
 import shutil
-import six
 import subunit
 import sys
 
@@ -144,13 +143,7 @@ class FileProvider(SubunitProvider):
 class StandardInputProvider(SubunitProvider):
     def __init__(self):
         self.buffer = BytesIO()
-        # Subunit is a binary protocol we need to ensure we read
-        # the contents as binary. On python3 this requires we use
-        # the stdin.buffer object as stdin is encoded otherwise.
-        if six.PY3:
-            shutil.copyfileobj(sys.stdin.buffer, self.buffer)
-        else:
-            shutil.copyfileobj(sys.stdin, self.buffer)
+        shutil.copyfileobj(sys.stdin.buffer, self.buffer)
         self.buffer.seek(0)
 
     @property