chore: remove dead and py2 compatibility code

form_grid_template doesn't exist
diff --git a/erpnext/manufacturing/doctype/work_order/work_order.py b/erpnext/manufacturing/doctype/work_order/work_order.py
index e343ed2..3027532 100644
--- a/erpnext/manufacturing/doctype/work_order/work_order.py
+++ b/erpnext/manufacturing/doctype/work_order/work_order.py
@@ -1,7 +1,6 @@
-# Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
+# Copyright (c) 2021, Frappe Technologies Pvt. Ltd. and Contributors
 # License: GNU General Public License v3. See license.txt
 
-from __future__ import unicode_literals
 import frappe
 import json
 import math
@@ -30,9 +29,6 @@
 class SerialNoQtyError(frappe.ValidationError):
 	pass
 
-form_grid_templates = {
-	"operations": "templates/form_grid/work_order_grid.html"
-}
 
 class WorkOrder(Document):
 	def onload(self):