MsgPack: set default log level to WARN to avoid CI issues (2)

Missed this spot while setting the default log level for MsgPack to
avoid a warning on every CI run.

Signed-off-by: Luca Burelli <l.burelli@arduino.cc>

Author: pillo79

src/error.h

@@ -14,6 +14,9 @@
 
 #include <utility>
 
+// MsgPack log level
+#define DEBUGLOG_DEFAULT_LOG_LEVEL_WARN
+
 #include "MsgPack.h"
 
 #define NO_ERR                   0x00
@@ -43,4 +46,4 @@ struct RpcError {
     MSGPACK_DEFINE(code, traceback); // -> [code, traceback]
 };
 
-#endif
+#endif