textproc/html-xml-utils: update to 8.7

Upstream changes:

2025-02-16 Bert Bos <bert@w3.org>

• Released version 8.7
• textwrap.c: Corrected counting of visible characters on a line (bufchars).

2023-10-24 Bert Bos <bert@w3.org>

• hxcopy.c: Fixed error in an error message.

PR: 284894
MFH: 2025Q1
(cherry picked from commit 7ce0a19113ea539f1a6e6222b9c8c4b81ee1af37)