www/py-notebook: Update to 6.4.12

Changes:	https://github.com/jupyter/notebook/releases

www/py-notebook/Makefile

 PORTNAME=	notebook
-PORTVERSION=	6.4.11
+PORTVERSION=	6.4.12
 CATEGORIES=	www python
 MASTER_SITES=	CHEESESHOP
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}

www/py-notebook/distinfo

-TIMESTAMP = 1650970331
-SHA256 (notebook-6.4.11.tar.gz) = 709b1856a564fe53054796c80e17a67262071c86bfbdfa6b96aaa346113c555a
-SIZE (notebook-6.4.11.tar.gz) = 14373938
+TIMESTAMP = 1654708460
+SHA256 (notebook-6.4.12.tar.gz) = 6268c9ec9048cff7a45405c990c29ac9ca40b0bc3ec29263d218c5e01f2b4e86
+SIZE (notebook-6.4.12.tar.gz) = 14389641