fix: ensure payload size check respects PostgreSQL NOTIFY limit (#17)

The previous check used `>` instead of `>=` with a default threshold of 8000 bytes. 
Since PostgreSQL's `NOTIFY` command has a strict limit of 7999 bytes, a payload 
of exactly 8000 bytes would bypass the attachment logic and cause the query 
to fail.

Author: sjoerdsmink

lib/util.ts

@@ -170,7 +170,7 @@ export class PubSubClient {
       }
 
       const payload = JSON.stringify(message);
-      if (Buffer.byteLength(payload) > this.opts.payloadThreshold) {
+      if (Buffer.byteLength(payload) >= this.opts.payloadThreshold) {
         return this.publishWithAttachment(message);
       }