Remove the JoinManager class

It doesn't add anything that an autogenerated manager cannot provide.

model_utils/managers.py

@@ -382,18 +382,3 @@ class Meta:
         )
         new_qs.query.join(conn, reuse=None)
         return new_qs
-
-
-class JoinManagerMixin:
-    """
-    Manager that adds a method join. This method allows you to join two
-    querysets together.
-    """
-    _queryset_class = JoinQueryset
-
-    def get_queryset(self):
-        return self._queryset_class(model=self.model, using=self._db)
-
-
-class JoinManager(JoinManagerMixin, models.Manager):
-    pass

tests/models.py

@@ -9,7 +9,7 @@
 
 from model_utils import Choices
 from model_utils.fields import MonitorField, SplitField, StatusField, UUIDField
-from model_utils.managers import InheritanceManager, JoinManager, QueryManager
+from model_utils.managers import InheritanceManager, JoinQueryset, QueryManager
 from model_utils.models import (
     SoftDeletableModel,
     StatusModel,
@@ -394,7 +394,7 @@ class ModelWithCustomDescriptor(models.Model):
 
 class BoxJoinModel(models.Model):
     name = models.CharField(max_length=32)
-    objects: ClassVar[JoinManager[BoxJoinModel]] = JoinManager()
+    objects = JoinQueryset.as_manager()
 
 
 class JoinItemForeignKey(models.Model):
@@ -404,7 +404,7 @@ class JoinItemForeignKey(models.Model):
         null=True,
         on_delete=models.CASCADE
     )
-    objects: ClassVar[JoinManager[JoinItemForeignKey]] = JoinManager()
+    objects = JoinQueryset.as_manager()
 
 
 class CustomUUIDModel(UUIDModel):