replace unicode call with force_text

rest_framework/utils/formatting.py

@@ -5,6 +5,8 @@ from __future__ import unicode_literals
 
 from django.utils.html import escape
 from django.utils.safestring import mark_safe
+from django.utils.encoding import force_text
+
 from rest_framework.compat import apply_markdown
 import re
 
@@ -28,7 +30,7 @@ def dedent(content):
     as it fails to dedent multiline docstrings that include
     unindented text on the initial line.
     """
-    content = unicode(content)
+    content = force_text(content)
     whitespace_counts = [len(line) - len(line.lstrip(' '))
                          for line in content.splitlines()[1:] if line.lstrip()]