data: json: include missing toolchain.h

This header is needed in order to use __deprecated macro.

Signed-off-by: Marcin Niestroj <[email protected]>

Author: mniestroj

include/data/json.h

@@ -9,6 +9,7 @@
 
 #include <sys/util.h>
 #include <stddef.h>
+#include <toolchain.h>
 #include <zephyr/types.h>
 #include <sys/types.h>