fix: cannot update auth token until token expiry if credentials change

erpnext/regional/doctype/e_invoice_settings/e_invoice_settings.py

@@ -10,3 +10,8 @@ class EInvoiceSettings(Document):
 	def validate(self):
 		if self.enable and not self.credentials:
 			frappe.throw(_("You must add atleast one credentials to be able to use E Invoicing."))
+
+		prev_doc = self.get_doc_before_save()
+		if prev_doc.client_secret != self.client_secret or prev_doc.client_id != prev_doc.client_id:
+			self.auth_token = None
+			self.token_expiry = None