feat: add support for string_view as D-Bus type

include/sdbus-c++/Message.h

@@ -100,6 +100,7 @@ namespace sdbus {
         Message& operator<<(double item);
         Message& operator<<(const char *item);
         Message& operator<<(const std::string &item);
+        Message& operator<<(std::string_view item);
         Message& operator<<(const Variant &item);
         template <typename ...Elements>
         Message& operator<<(const std::variant<Elements...>& value);

include/sdbus-c++/TypeTraits.h

@@ -41,6 +41,7 @@
 #  endif
 #endif
 #include <string>
+#include <string_view>
 #include <tuple>
 #include <type_traits>
 #include <unordered_map>
@@ -231,6 +232,10 @@ namespace sdbus {
         static constexpr bool is_trivial_dbus_type = false;
     };
 
+    template <>
+    struct signature_of<std::string_view> : signature_of<std::string>
+    {};
+
     template <>
     struct signature_of<char*> : signature_of<std::string>
     {};