Add psycopg2 to requirements

[assumptionsandg]

Add psycopg2 to requirements for postgresql support to avoid error

File "/venv/lib/python3.10/site-packages/django/db/backends/postgresql/base.py", line 29, in <module>                             
raise ImproperlyConfigured("Error loading psycopg2 or psycopg module")                                                          
django.core.exceptions.ImproperlyConfigured: Error loading psycopg2 or psycopg module

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[JohnGarbutt]

Lets add in this extra dependency