[#634] Fix std::forward usage

Author: mikir

compiler/extensions/cpp/runtime/src/zserio/JsonDecoder.h

@@ -67,7 +67,7 @@ class BasicJsonDecoder : public AllocatorHolder<ALLOC>
         template <typename T>
         DecoderResult(size_t numRead, T&& decodedValue, bool overflow, const ALLOC& allocator) :
                 numReadChars(numRead),
-                value(createValue(decodedValue, overflow, allocator)),
+                value(createValue(std::forward<T>(decodedValue), overflow, allocator)),
                 integerOverflow(overflow)
         {}