Support for Django 4 (#101)

* Support for Django 4

* Change pytest-django version

* Change psycopg2 version

* Change pytest version

* Change tox version

* Change pytest-cov version

* Update circle ci jobs

* Fix ci jobs

* Update ci to postgres 12

* Allow Django 5.0

* Bump Django min version to 3.2

* Fix CI to account for >= 3.2 requirement

* Fix quote

* Remove python 3.12 for now due to distutils removal

* Remove Django upper bound

* Add back python3.6,3.7 wfs

* Downgrade dj-database-url

* Fix isnull issue from Django 4

localized_fields/lookups.py

@@ -43,6 +43,10 @@ class LocalizedLookupMixin:
         return super().process_lhs(qn, connection)
 
     def get_prep_lookup(self):
+        # Django 4.0 removed the ability for isnull fields to be something other than a bool
+        # We should NOT convert them to strings
+        if isinstance(self.rhs, bool):
+            return self.rhs
         return str(self.rhs)