chore: remove unused reference to Sarg Squid Analyzer, because package is not available in Bullseye

tasks/install-packages.yml

 ---
-- name: install packages (rsync, sarg, squid3, tar, unzip)
+- name: install packages (rsync, squid3, tar, unzip)
   ansible.builtin.apt:
     state: present
     name: [
       'rsync',
-      # 'sarg',      # https://www.tecmint.com/sarg-squid-analysis-report-generator-and-internet-bandwidth-monitoring-tool/
       'squid',
       'tar',
       'unzip'