chore: add temporary workaround to expose PDO exceptions from commits

these are caused by postgres constraint issues, and are not currently
handled well by doctrine:

doctrine#7545

src/UnitOfWork.php

@@ -482,7 +482,11 @@ public function commit($entity = null)
             $this->em->close();
 
             if ($conn->isTransactionActive()) {
-                $conn->rollBack();
+                try {
+                    $conn->rollBack();
+                } catch (Exception) {
+                    // Swallow to preserve commit exception.
+                }
             }
 
             $this->afterTransactionRolledBack();