clang-tidy: fix incorrect conversion unsigned->int

alib2measure/src/measurements/MeasurementFrame.cpp

@@ -19,7 +19,7 @@ std::ostream & operator <<( std::ostream & os, const MeasurementFrame & frame )
 	os << "(" << frame.name << ", " << frame.type << ", " << frame.parentIdx << ", [";
 	bool first = true;
-	for ( int subId : frame.subIdxs ) {
+	for ( unsigned subId : frame.subIdxs ) {
 		if ( first )
 			first = false;
 		else