Update requirements.txt

Author: pmasl

samples/development-frameworks/django/requirements.txt

@@ -6,6 +6,6 @@ Unipath==1.0
 python-decouple==3
 Pillow==3.3.2
 Markdown==2.6.6
-bleach==1.4.3
+bleach==3.3.0
 django-pyodbc-azure==1.9.6.0
 whitenoise==3.2