Remove Werkzeug dependency, creates security errors. (#4122)

If you want to use Werkzeug please install yourselves in development environment

requirements.txt

 # These requirements are only necessary when developing on Oscar.
 
 # development
-Werkzeug>=1.0,<2.1
 django-debug-toolbar>=2.2,<4.1
 django-extensions>=2.2,<3.3
 psycopg2-binary>=2.8,<2.10