Codechange: use std::string without const as return

Otherwise some compilers, e.g. MSVC, do not pick up that these are temporaries
and as such it will pass the temporaries to `const std::string &` instead of
the wanted `std::string &&`

src/script/api/script_text.cpp

@@ -158,7 +158,7 @@ SQInteger ScriptText::_set(HSQUIRRELVM vm)
 	return this->_SetParam(k, vm);
 }
 
-const std::string ScriptText::GetEncodedText()
+std::string ScriptText::GetEncodedText()
 {
 	static StringIDList seen_ids;
 	int param_count = 0;