sysutils/py-mqttwarn: Update to 0.31.0

https://github.com/jpmens/mqttwarn/releases/tag/0.31.0

sysutils/py-mqttwarn/Makefile

 PORTNAME=	mqttwarn
-DISTVERSION=	0.29.1
+DISTVERSION=	0.31.0
 CATEGORIES=	sysutils python
 MASTER_SITES=	CHEESESHOP
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}

sysutils/py-mqttwarn/distinfo

-TIMESTAMP = 1661192466
-SHA256 (mqttwarn-0.29.1.tar.gz) = 2c6be72eda1ddec42e91148b444f15eee99d3c4380d090c1cd97aada85304a04
-SIZE (mqttwarn-0.29.1.tar.gz) = 121082
+TIMESTAMP = 1669052917
+SHA256 (mqttwarn-0.31.0.tar.gz) = 22a12c086221dc45a38d0a4970d169fd5b28d55a34318e0d398ecee008f24519
+SIZE (mqttwarn-0.31.0.tar.gz) = 123927