Update lead.py (#8789)

* Update lead.py

Import datetime to compare next contact date with now()

* Update lead.py

* Update lead.py

As per the suggestion from Nabin,instead of Datetime,getdate and nowdate from frappe.utils imported
diff --git a/erpnext/crm/doctype/lead/lead.py b/erpnext/crm/doctype/lead/lead.py
index e6659f3..a37caea 100644
--- a/erpnext/crm/doctype/lead/lead.py
+++ b/erpnext/crm/doctype/lead/lead.py
@@ -4,7 +4,7 @@
 from __future__ import unicode_literals
 import frappe
 from frappe import _
-from frappe.utils import (cstr, validate_email_add, cint, comma_and, has_gravatar, now)
+from frappe.utils import (cstr, validate_email_add, cint, comma_and, has_gravatar, now, getdate, nowdate)
 from frappe.model.mapper import get_mapped_doc
 
 from erpnext.controllers.selling_controller import SellingController
@@ -45,7 +45,7 @@
 
 			self.image = has_gravatar(self.email_id)
 
-		if self.contact_date and self.contact_date < now():
+		if self.contact_date and getdate(self.contact_date) < getdate(nowdate()):
 			frappe.throw(_("Next Contact Date cannot be in the past"))
 
 	def on_update(self):