Add transaction handling for non-replica set MongoDB connections

Author: shimonewman

src/Database/Adapter/Mongo.php

@@ -125,6 +125,12 @@ public function withTransaction(callable $callback): mixed
 
     public function startTransaction(): bool
     {
+
+         // If the database is not a replica set, we can't use transactions
+         if (!$this->client->isReplicaSet()) {
+            return false;
+        }
+
         try {
             if ($this->inTransaction === 0) {
                 if (!$this->sessionId) {