Add [[maybe_unused]] to silence unhelpful warnings

handlers/handlerversion.cpp

@@ -1,6 +1,6 @@
 #include "handlerversion.h"
 #include "../version.h"
-Response HandlerVersion::handleRequest(const Request &r)
+Response HandlerVersion::handleRequest([[maybe_unused]] const Request &r)
 {
 	Response response;
 	response.setContentType("text/plain");