Remove BaseDatabaseWrapper from compat

Author: michael-k

pytest_django/compat.py

@@ -1,6 +1,4 @@
 # This file cannot be imported from until Django sets up
-from django.db.backends.base.base import BaseDatabaseWrapper
-
 try:
     # Django 1.11
     from django.test.utils import setup_databases, teardown_databases  # noqa

pytest_django/plugin.py

@@ -600,7 +600,7 @@ def __init__(self):
 
     @property
     def _dj_db_wrapper(self):
-        from .compat import BaseDatabaseWrapper
+        from django.db.backends.base.base import BaseDatabaseWrapper
 
         # The first time the _dj_db_wrapper is accessed, we will save a
         # reference to the real implementation.