polish/libtlen: Mark DEPRECATED

- Last upstream release was in 2004
- The mentioned also seems to be defunct as I could not find any source
- Set EXPIRATION_DATE to 2023-12-05

Approved by:    portmgr (blanket)

polish/libtlen/Makefile

@@ -8,6 +8,9 @@ MAINTAINER=	ports@FreeBSD.org
 COMMENT=	Backend for interoperability with Tlen.pl, Polish IM network
 WWW=		https://libtlen.sourceforge.net/
 
+DEPRECATED=	Last upstream release was in 2004
+EXPIRATION_DATE=	2023-12-05
+
 GNU_CONFIGURE=	yes
 USE_LDCONFIG=	yes