Shut down the EventLoopGroupConnectionPool using an API that doesn't …

…call EventLoopFuture.wait() internally.

Sources/FluentMySQLDriver/FluentMySQLDriver.swift

@@ -27,6 +27,6 @@ struct _FluentMySQLDriver: DatabaseDriver {
 
     // See `DatabaseDriver.shutdown()`.
     func shutdown() {
-        self.pool.shutdown()
+        try? self.pool.syncShutdownGracefully()
     }
 }