Add 1.13.0 changelog

docs/changelog.rst

@@ -3,6 +3,18 @@ Changelog
 #########
 
 
+**********
+**1.13.0**
+**********
+
+*Release date: Jan 29, 2019*
+
+- **IMPROVED:** type hint inspection is now supported for collections and``Optional`` (:pr:`272`)
+- **IMPROVED:** updated ``swagger-ui`` to version 3.20.5
+- **IMPROVED:** updated ``ReDoc`` to version 2.0.0-rc.2
+- **DEPRECATED:** quietly dropped support for the ``flex`` validator; it will still work if the library is installed,
+  but the setup.py requirement was removed and the validator will be silently skipped if not installed (:issue:`285`)
+
 **********
 **1.12.1**
 **********

src/drf_yasg/inspectors/view.py

@@ -1,5 +1,4 @@
 import logging
-import warnings
 from collections import OrderedDict
 
 from rest_framework.request import is_form_media_type