remove jsonb, because the extra lib support

docs/fields/field-types.md

@@ -140,13 +140,6 @@ You can pass `timezone=True` for timezone aware database column.
 * Sqlalchemy column: `sqlalchemy.JSON`  
 * Type (used for pydantic): `pydantic.Json` 
 
-### JSONB
-
-`JSONB()` has no required parameters, only support it in the postgresql.
-
-* Sqlalchemy column: `sqlalchemy.dialects.postgresql.JSONB`  
-* Type (used for pydantic): `pydantic.Json` 
-
 ### LargeBinary
 
 `LargeBinary(max_length)` has a required `max_length` parameter.  

ormar/fields/model_fields.py

@@ -520,29 +520,6 @@ class JSON(ModelFieldFactory, pydantic.Json):
         return sqlalchemy.JSON()
 
 
-class JSONB(JSON):
-    """
-    JSONB field factory that construct Field classes and populated their values,
-    only support postgresql
-    """
-
-    _type = pydantic.Json
-    _sample = '{"jsonb": "jsonb"}'
-
-    @classmethod
-    def get_column_type(cls, **kwargs: Any) -> Any:
-        """
-        Return proper type of db column for given field type.
-        Accepts required and optional parameters that each column type accepts.
-
-        :param kwargs: key, value pairs of sqlalchemy options
-        :type kwargs: Any
-        :return: initialized column with proper options
-        :rtype: sqlalchemy Column
-        """
-        return sqlalchemy.dialects.postgresql.JSONB()
-
-
 if TYPE_CHECKING:  # pragma: nocover # noqa: C901
 
     @overload