Use Unicode typography in new translatable strings

See https://developer.gnome.org/hig/stable/typography.html

gio/gdbusconnection.c

@@ -4619,7 +4619,7 @@ handle_get_all_properties (GDBusConnection *connection,
       GDBusMessage *reply;
       reply = g_dbus_message_new_method_error (message,
                                                "org.freedesktop.DBus.Error.InvalidArgs",
-                                               _("No such interface '%s'"),
+                                               _("No such interface “%s”"),
                                                interface_name);
       g_dbus_connection_send_message_unlocked (eo->connection, reply, G_DBUS_SEND_MESSAGE_FLAGS_NONE, NULL, NULL);
       g_object_unref (reply);

gio/glib-compile-schemas.c

@@ -1982,7 +1982,7 @@ set_overrides (GHashTable  *schema_table,
                    */
                   fprintf (stderr,
                            _("cannot provide per-desktop overrides for localised "
-                             "key '%s' in schema '%s' (override file '%s')"),
+                             "key “%s” in schema “%s” (override file “%s”)"),
                            key, group, filename);
 
                   if (!strict)

glib/gspawn.c

@@ -1593,7 +1593,7 @@ fork_exec_with_fds (gboolean              intermediate_child,
           g_set_error (error,
                        G_SPAWN_ERROR,
                        G_SPAWN_ERROR_FAILED,
-                       _("Failed to spawn child process \"%s\" (%s)"),
+                       _("Failed to spawn child process “%s” (%s)"),
                        argv[0],
                        g_strerror (status));
           return FALSE;