chore(pegboard): consolidate to single subscriber per gateway (#2879)

Author: NathanFlurry

packages/common/universalpubsub/src/driver/postgres/mod.rs

@@ -1,6 +1,6 @@
 use std::collections::HashMap;
 use std::hash::{DefaultHasher, Hash, Hasher};
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 
 use anyhow::*;
 use async_trait::async_trait;