fix: check null values in is_cancelled patch (#30594)

diff --git a/erpnext/patches/v12_0/update_is_cancelled_field.py b/erpnext/patches/v12_0/update_is_cancelled_field.py
index b567823..398dd70 100644
--- a/erpnext/patches/v12_0/update_is_cancelled_field.py
+++ b/erpnext/patches/v12_0/update_is_cancelled_field.py
@@ -20,7 +20,7 @@
 			"""
 				UPDATE `tab{doctype}`
 				SET is_cancelled = 0
-				where is_cancelled in ('', NULL, 'No')""".format(
+				where is_cancelled in ('', 'No') or is_cancelled is NULL""".format(
 				doctype=doctype
 			)
 		)
diff --git a/erpnext/patches/v14_0/change_is_subcontracted_fieldtype.py b/erpnext/patches/v14_0/change_is_subcontracted_fieldtype.py
index ba919a7..9b07ba8 100644
--- a/erpnext/patches/v14_0/change_is_subcontracted_fieldtype.py
+++ b/erpnext/patches/v14_0/change_is_subcontracted_fieldtype.py
@@ -10,7 +10,7 @@
 			"""
 				UPDATE `tab{doctype}`
 				SET is_subcontracted = 0
-				where is_subcontracted in ('', NULL, 'No')""".format(
+				where is_subcontracted in ('', 'No') or is_subcontracted is null""".format(
 				doctype=doctype
 			)
 		)