refactor: doctype naming

Overdue Payments -> Overdue Payment

erpnext/accounts/doctype/dunning/dunning.json

@@ -276,7 +276,7 @@
    "fieldname": "overdue_payments",
    "fieldtype": "Table",
    "label": "Overdue Payments",
-   "options": "Overdue Payments"
+   "options": "Overdue Payment"
   },
   {
    "fieldname": "section_break_28",
@@ -313,7 +313,7 @@
  ],
  "is_submittable": 1,
  "links": [],
- "modified": "2021-09-15 19:08:22.913539",
+ "modified": "2021-09-16 14:06:48.472825",
  "modified_by": "Administrator",
  "module": "Accounts",
  "name": "Dunning",

erpnext/accounts/doctype/overdue_payment/overdue_payment.json

@@ -161,7 +161,7 @@
  "modified": "2021-09-15 19:04:54.082880",
  "modified_by": "Administrator",
  "module": "Accounts",
- "name": "Overdue Payments",
+ "name": "Overdue Payment",
  "owner": "Administrator",
  "permissions": [],
  "quick_entry": 1,

erpnext/accounts/doctype/overdue_payment/overdue_payment.py

@@ -4,5 +4,5 @@
 # import frappe
 from frappe.model.document import Document
 
-class OverduePayments(Document):
+class OverduePayment(Document):
 	pass