fix(demo): Item creation with India Compliance app (#36627)

diff --git a/erpnext/setup/demo_data/item.json b/erpnext/setup/demo_data/item.json
index ffe4152..330e114 100644
--- a/erpnext/setup/demo_data/item.json
+++ b/erpnext/setup/demo_data/item.json
@@ -4,6 +4,7 @@
         "item_group": "Demo Item Group",
         "item_code": "SKU001",
         "item_name": "T-shirt",
+        "gst_hsn_code": "999512",
         "image": "https://images.pexels.com/photos/1484808/pexels-photo-1484808.jpeg"
     },
     {
@@ -11,6 +12,7 @@
         "item_group": "Demo Item Group",
         "item_code": "SKU002",
         "item_name": "Laptop",
+        "gst_hsn_code": "999512",
         "image": "https://images.pexels.com/photos/3999538/pexels-photo-3999538.jpeg"
     },
     {
@@ -18,6 +20,7 @@
         "item_group": "Demo Item Group",
         "item_code": "SKU003",
         "item_name": "Book",
+        "gst_hsn_code": "999512",
         "image": "https://images.pexels.com/photos/2422178/pexels-photo-2422178.jpeg"
     },
     {
@@ -25,6 +28,7 @@
         "item_group": "Demo Item Group",
         "item_code": "SKU004",
         "item_name": "Smartphone",
+        "gst_hsn_code": "999512",
         "image": "https://images.pexels.com/photos/1647976/pexels-photo-1647976.jpeg"
     },
     {
@@ -32,6 +36,7 @@
         "item_group": "Demo Item Group",
         "item_code": "SKU005",
         "item_name": "Sneakers",
+        "gst_hsn_code": "999512",
         "image": "https://images.pexels.com/photos/1598505/pexels-photo-1598505.jpeg"
     },
     {
@@ -39,6 +44,7 @@
         "item_group": "Demo Item Group",
         "item_code": "SKU006",
         "item_name": "Coffee Mug",
+        "gst_hsn_code": "999512",
         "image": "https://images.pexels.com/photos/585753/pexels-photo-585753.jpeg"
     },
     {
@@ -46,6 +52,7 @@
         "item_group": "Demo Item Group",
         "item_code": "SKU007",
         "item_name": "Television",
+        "gst_hsn_code": "999512",
         "image": "https://images.pexels.com/photos/8059376/pexels-photo-8059376.jpeg"
     },
     {
@@ -53,6 +60,7 @@
         "item_group": "Demo Item Group",
         "item_code": "SKU008",
         "item_name": "Backpack",
+        "gst_hsn_code": "999512",
         "image": "https://images.pexels.com/photos/3731256/pexels-photo-3731256.jpeg"
     },
     {
@@ -60,6 +68,7 @@
         "item_group": "Demo Item Group",
         "item_code": "SKU009",
         "item_name": "Headphones",
+        "gst_hsn_code": "999512",
         "image": "https://images.pexels.com/photos/3587478/pexels-photo-3587478.jpeg"
     },
     {
@@ -67,6 +76,7 @@
         "item_group": "Demo Item Group",
         "item_code": "SKU010",
         "item_name": "Camera",
+        "gst_hsn_code": "999512",
         "image": "https://images.pexels.com/photos/51383/photo-camera-subject-photographer-51383.jpeg"
     }
 ]