fix: use proper string concatenation for error on unsupported types

The previous default template instances of `decodeType` for parametrized
types used a "concatenation" on two char pointers, which doesn't work.
This PR fixes that by making one of the two an `std::string`. The error
did not show up until now because all supported types have
specializations of the template.

Signed-off-by: Ingo Müller <ingomueller@google.com>

src/substrait/type/Type.cpp

@@ -40,7 +40,7 @@ ParameterizedTypePtr decodeType(
     bool nullable,
     const std::vector<ParameterizedTypePtr>& parameterTypes) {
   SUBSTRAIT_UNSUPPORTED(
-      "Unsupported parameter type: " + TypeTraits<Kind>::kTypeString);
+      std::string("Unsupported parameter type: ") + TypeTraits<Kind>::kTypeString);
 }
 
 template <>