fix: activate_z_coin_light_with_changing_height

i confused min with max when fixing this potential panic. max is the one we want here, so that when we have 0.max(1) we get 1 and not 0

mm2src/coins/utxo/utxo_builder/utxo_coin_builder.rs

@@ -775,7 +775,7 @@ pub trait UtxoCoinBuilderCommonOps {
         };
 
         let secs_since_date = current_time_sec - date_s;
-        let days_since_date = (secs_since_date / DAY_IN_SECONDS).min(1) - 1;
+        let days_since_date = (secs_since_date / DAY_IN_SECONDS).max(1) - 1;
         let blocks_to_sync = (days_since_date * blocks_per_day) + blocks_per_day;
 
         if current_block_height < blocks_to_sync {