net/tcpslice: Update to 1.6 and use upstream release archive

Changelog:
https://github.com/the-tcpdump-group/tcpslice/blob/tcpslice-1.6/CHANGES

PR:		262723
Approved by:	portmgr (maintainer timeout, 2+ weeks)

net/tcpslice/Makefile

@@ -1,7 +1,8 @@
 PORTNAME=	tcpslice
-PORTVERSION=	1.5
+DISTVERSION=	1.6
 PORTEPOCH=	1
 CATEGORIES=	net
+MASTER_SITES=	https://www.tcpdump.org/release/
 
 MAINTAINER=	sbz@FreeBSD.org
 COMMENT=	Tool for extracting portions of pcap files
@@ -18,8 +19,4 @@ PLIST_FILES=	bin/tcpslice \
 
 GNU_CONFIGURE=	yes
 
-USE_GITHUB=	yes
-GH_ACCOUNT=	the-tcpdump-group
-GH_TAGNAME=	f73194c
-
 .include <bsd.port.mk>

net/tcpslice/distinfo

@@ -1,3 +1,3 @@
-TIMESTAMP = 1647963550
-SHA256 (the-tcpdump-group-tcpslice-1.5-f73194c_GH0.tar.gz) = 8008205b41b04aafd469e6cc1306fea884e3b80f993812272c82afce83ae560e
-SIZE (the-tcpdump-group-tcpslice-1.5-f73194c_GH0.tar.gz) = 141975
+TIMESTAMP = 1673203793
+SHA256 (tcpslice-1.6.tar.gz) = 60d23f00d4c485fef2dda9b12c2018af958df3a511238c45374733bbc1231920
+SIZE (tcpslice-1.6.tar.gz) = 140775