[LXC] ubuntu 20.10 EOL, upgrade to ubunut 21.10 [1]

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

Tested by::

    # build the container ..
    $ sudo -H ./utils/lxc.sh build searx-ubu2110

    # open a shell in the container
    $ sudo -H ./utils/lxc.sh cmd searx-ubu2110 bash
    [root@searx-ubu2110 SearXNG]#

    # install a complete SearXNG suite ..
    [root@searx-ubu2110 SearXNG]# ./utils/searx.sh install all
    ...

    # install apache to export the SearXNG instance by HTTP
    [root@searx-ubu2110 SearXNG]# ./utils/searx.sh apache install
    ...
    INFO:  got 200 from http://10.174.184.94/searx

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

utils/lxc-searx.env

@@ -23,7 +23,7 @@ lxc_set_suite_env() {
         # end of standard support see https://wiki.ubuntu.com/Releases
         "$LINUXCONTAINERS_ORG_NAME:ubuntu/18.04"  "ubu1804" # April 2023
         "$LINUXCONTAINERS_ORG_NAME:ubuntu/20.04"  "ubu2004" # April 2025
-        "$LINUXCONTAINERS_ORG_NAME:ubuntu/20.10"  "ubu2010" # July 2021
+        "$LINUXCONTAINERS_ORG_NAME:ubuntu/21.10"  "ubu2110" # July 2027
 
         # EOL see https://fedoraproject.org/wiki/Releases
         "$LINUXCONTAINERS_ORG_NAME:fedora/35"     "fedora35"

utils/lxc.sh

@@ -41,7 +41,7 @@ echo 'Set disable_coredump false' >> /etc/sudo.conf
 "
 
 # shellcheck disable=SC2034
-ubu2010_boilerplate="$ubu1904_boilerplate"
+ubu2110_boilerplate="$ubu1904_boilerplate"
 
 # shellcheck disable=SC2034
 archlinux_boilerplate="