devel/libtar: Deprecate and set expiration date to 2023-09-30

Abandonware since 2013 and multiple CVEs over the years

References:
https://www.opencve.io/cve?vendor=feep&product=libtar

PR:		272304
Approved by:	portmgr (maintainer timeout, 2+ weeks)

devel/libtar/Makefile

@@ -10,6 +10,9 @@ WWW=		https://repo.or.cz/w/libtar.git
 LICENSE=	BSD3CLAUSE
 LICENSE_FILE=	${WRKSRC}/COPYRIGHT
 
+DEPRECATED=	Abandonware since 2013 and multiple CVEs over the years
+EXPIRATION_DATE=2023-09-30
+
 USES=		autoreconf cpe gmake libtool
 USE_LDCONFIG=	yes