Use updated types-psycopg2 from typeshed (typeddjango#196)

This finishes the work done in typeddjango#126. Commits are cherry-picked to give the original author credit.

I also removed psycopg2 tests as they are typeshed's problem now.

Fixes typeddjango#74
Closes typeddjango#126

Author: hamdanal

.ignore

@@ -1,2 +1 @@
 django-stubs
-psycopg2-stubs

django-stubs/db/backends/utils.pyi

@@ -6,7 +6,7 @@ from typing import IO, Any
 from typing_extensions import Literal
 from uuid import UUID
 
-import psycopg2
+import psycopg2.extensions
 from django.db.backends.postgresql.base import DatabaseWrapper
 from psycopg2.extensions import Column