net/asterisk20: Update 20.14.1 → 20.15.0 (security fix)

GHSA-c7p6-7mvq-8jq2: cli_permissions.conf: deny option does not work
for disallowing shell commands

Change Log:
https://downloads.asterisk.org/pub/telephony/asterisk/releases/ChangeLog-20.15.0.html

PR: 288429
Security: GHSA-c7p6-7mvq-8jq2
Sponsored by: FLEX-IT LLC
MFH: 2025Q3

(cherry picked from commit 95ebee717d8fdb0db2ac28b8e65d713f81a75052)