fix: rate and amount in material request copying from sales order (#20717)

erpnext/stock/doctype/material_request_item/material_request_item.json

@@ -1,4 +1,5 @@
 {
+ "actions": [],
  "autoname": "hash",
  "creation": "2013-02-22 01:28:02",
  "doctype": "DocType",
@@ -185,12 +186,14 @@
   {
    "fieldname": "rate",
    "fieldtype": "Currency",
-   "label": "Rate"
+   "label": "Rate",
+   "no_copy": 1
   },
   {
    "fieldname": "amount",
    "fieldtype": "Currency",
    "label": "Amount",
+   "no_copy": 1,
    "read_only": 1
   },
   {
@@ -407,7 +410,8 @@
  ],
  "idx": 1,
  "istable": 1,
- "modified": "2019-06-02 06:49:36.493957",
+ "links": [],
+ "modified": "2020-02-25 03:09:10.698967",
  "modified_by": "Administrator",
  "module": "Stock",
  "name": "Material Request Item",