Use cw_serde on counter state example

Author: CyberHoward

contracts-ws/contracts/counter/src/state.rs

@@ -1,10 +1,9 @@
-use schemars::JsonSchema;
-use serde::{Deserialize, Serialize};
+use cosmwasm_schema::cw_serde;
 
 use cosmwasm_std::Addr;
 use cw_storage_plus::Item;
 
-#[derive(Serialize, Deserialize, Clone, Debug, PartialEq, Eq, JsonSchema)]
+#[cw_serde]
 pub struct State {
     pub count: i32,
     pub owner: Addr,