[LXC] ubuntu 21.10 upgrade to ubuntu 22.04 LTS [1]

[1] https://wiki.ubuntu.com/Releases



Tested by::

    # build the container ..
    $ sudo -H ./utils/lxc.sh build searxng-ubu2204

    # install a complete SearXNG suite ..
    $ sudo -H ./utils/lxc.sh cmd searxng-ubu2204 FORCE_TIMEOUT=0 ./utils/searxng.sh install all

    # install nginx to export the SearXNG instance by HTTP
    $ sudo -H ./utils/lxc.sh cmd searxng-ubu2204 FORCE_TIMEOUT=0 ./utils/searxng.sh install nginx

    # check instance
    $  sudo -H ./utils/lxc.sh cmd searxng-ubu2204 FORCE_TIMEOUT=0 ./utils/searxng.sh instance check
    INFO:  [searxng-ubu2204] FORCE_TIMEOUT=0 ./utils/searxng.sh instance check
    INFO:  wrapper:  utils/searxng.sh instance _call searxng.check

    SearXNG checks
    --------------
    ...
    INFO    searx                         : merge the default settings ( /usr/local/searxng/searxng-src/searx/settings.yml ) and the user settings ( /etc/searxng/settings.yml )
    INFO    searx                         : max_request_timeout=None
    INFO    searx.redisdb                 : connecting to Redis db=0 path='/usr/local/searxng-redis/run/redis.sock'
    INFO    searx.redisdb                 : connected to Redis

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>