devel/py-nbdime: Update to 3.1.0

Changes:	https://github.com/jupyter/nbdime/blob/master/docs/source/changelog.md

devel/py-nbdime/Makefile

 # Created by: Po-Chuan Hsieh <sunpoet@FreeBSD.org>
 
 PORTNAME=	nbdime
-PORTVERSION=	3.0.0
-PORTREVISION=	1
+PORTVERSION=	3.1.0
 CATEGORIES=	devel python
 MASTER_SITES=	CHEESESHOP
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
@@ -21,7 +20,6 @@ RUN_DEPENDS=	${PYTHON_PKGNAMEPREFIX}colorama>=0:devel/py-colorama@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}nbformat>=0:devel/py-nbformat@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}pygments>=0:textproc/py-pygments@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}requests>=0:www/py-requests@${PY_FLAVOR} \
-		${PYTHON_PKGNAMEPREFIX}six>=0:devel/py-six@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}tornado>=0:www/py-tornado@${PY_FLAVOR}
 
 USES=		python:3.7+

devel/py-nbdime/distinfo

-TIMESTAMP = 1619198515
-SHA256 (nbdime-3.0.0.tar.gz) = 1777a7133c084a21f8e22f1be370436ae2fbde1991934170678fa8f826fd9b15
-SIZE (nbdime-3.0.0.tar.gz) = 7627985
+TIMESTAMP = 1622037976
+SHA256 (nbdime-3.1.0.tar.gz) = 12dc4390b355b26d07ac8d11d50efbcb54bae0ad5842b817131babd2f4567963
+SIZE (nbdime-3.1.0.tar.gz) = 7508382