Update ICRC-3.did

Author: MarioDfinity

standards/ICRC-3/ICRC-3.did

@@ -1,7 +1,7 @@
 type Value = variant {
     Blob : blob;
     Text : text;
-    Nat : nat; // do we need this or can we just use Int?
+    Nat : nat;
     Int : int;
     Array : vec Value;
     Map : vec record { text; Value };
@@ -54,4 +54,4 @@ service : {
   icrc3_get_tip_certificate : () -> (opt DataCertificate) query;
   icrc3_get_blocks : (GetBlocksArgs) -> (GetBlocksResult) query;
   icrc3_supported_block_types : () -> (vec record { block_type : text; url : text }) query;
-};
+};