requirements.txt upated to include django-taggit-serializers

requirements.txt

@@ -3,6 +3,7 @@ djangorestframework==3.6.3
 django-extensions==1.7.9
 django-imagekit==4.0
 django-taggit==0.22.0
+django-taggit-serializer
 Pillow==4.1.0
 selenium
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