fix(logging): prevent excessive MySQL warning logs

Lower MySQL warning log level from INFO to DEBUG to reduce log spam while maintaining debugging visibility.

Closes #311

Author: jchrys

r2dbc-mysql/src/main/java/io/asyncer/r2dbc/mysql/client/ReactorNettyClient.java

@@ -381,7 +381,7 @@ public void error(Throwable e) {
         public void next(ServerMessage message) {
             if (DEBUG_ENABLED) {
                 if (message instanceof WarningMessage) {
-                    int warnings = ((WarningMessage) message).getWarnings();
+                    final int warnings = ((WarningMessage) message).getWarnings();
                     if (warnings == 0) {
                         logger.debug("Response: {}", message);
                     } else {