Replaced types import with six (#3834)

Importing six.text_type instead of types.UnicodeType and
six.binary_type instead of types.StringType

frappe/database.py

@@ -18,7 +18,7 @@ import redis
 import frappe.model.meta
 from frappe.utils import now, get_datetime, cstr
 from frappe import _
-from types import StringType, UnicodeType
+from six import text_type, binary_type
 from frappe.utils.global_search import sync_global_search
 from frappe.model.utils.link_count import flush_local_link_count
 from six import iteritems, text_type
@@ -69,8 +69,8 @@ class Database:
 				use_unicode=True, charset='utf8mb4')
 		self._conn.converter[246]=float
 		self._conn.converter[12]=get_datetime
-		self._conn.encoders[UnicodeWithAttrs] = self._conn.encoders[UnicodeType]
-		self._conn.encoders[DateTimeDeltaType] = self._conn.encoders[StringType]
+		self._conn.encoders[UnicodeWithAttrs] = self._conn.encoders[text_type]
+		self._conn.encoders[DateTimeDeltaType] = self._conn.encoders[binary_type]
 
 		MYSQL_OPTION_MULTI_STATEMENTS_OFF = 1
 		self._conn.set_server_option(MYSQL_OPTION_MULTI_STATEMENTS_OFF)