res_ari_channels: Fix reference leak in channel_state_invalid.

channel_state_invalid leaked a reference to the channel snapshot any
time it was aquired.

ASTERISK-27067 #close

Change-Id: I8c653f00416b39978513c5605c4be0f03b1df29a

res/ari/resource_channels.c

@@ -99,9 +99,13 @@ static int channel_state_invalid(struct stasis_app_control *control,
 		|| snapshot->state == AST_STATE_RINGING) {
 		ast_ari_response_error(response, 412, "Precondition Failed",
 			"Channel in invalid state");
+		ao2_ref(snapshot, -1);
+
 		return -1;
 	}
 
+	ao2_ref(snapshot, -1);
+
 	return 0;
 }