MsgPack: set default log level to WARN to avoid CI issues

Not setting the default log level causes a warning on every CI run.
Setting it to WARN avoids the warning and is a reasonable default.

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

Author: pillo79

src/decoder.h

@@ -6,12 +6,14 @@
     This Source Code Form is subject to the terms of the Mozilla Public
     License, v. 2.0. If a copy of the MPL was not distributed with this
     file, You can obtain one at http://mozilla.org/MPL/2.0/.
-    
 */
 
 #ifndef RPCLITE_DECODER_H
 #define RPCLITE_DECODER_H
 
+// MsgPack log level
+#define DEBUGLOG_DEFAULT_LOG_LEVEL_WARN
+
 #include "MsgPack.h"
 #include "transport.h"
 #include "rpclite_utils.h"
@@ -343,4 +345,4 @@ class RpcDecoder {
 
 };
 
-#endif
+#endif