Add missing sudo_json_free().

lib/util/regress/json/json_test.c

@@ -224,6 +224,8 @@ main(int argc, char *argv[])
     }
 
 done:
+    sudo_json_free(&jsonc);
+
     if (ntests != 0) {
 	printf("%s: %d tests run, %d errors, %d%% success rate\n",
 	    getprogname(), ntests, errors, (ntests - errors) * 100 / ntests);