package/xterm: security bump to version 371

Fix CVE-2022-24130: xterm through Patch 370, when Sixel support is
enabled, allows attackers to trigger a buffer overflow in set_sixel in
graphics_sixel.c via crafted text.

Update hash of COPYING (update in year)

https://invisible-island.net/xterm/xterm.log.html#xterm_371



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>