🐛 Use bash as shell in cron jobs to make process substitution work

The cron jobs were executed, but dash (/bin/sh) complained, and so the
actual command was never run.  This is why our dyndns update did not
work through cron, but when executed manually in bash by an admin.

Example for such a fail when done manually in sh:

    # echo test3 > >(/usr/bin/logger -p user.debug -t dd24)
    /bin/sh: 7: Syntax error: redirection unexpected

Process substitution with `>(command)` is a feature supported by bash
and other shells, but not by POSIX shell which was supposed to used here
(set by `SHELL=…`).  Instead of building complicated redirect magic for
sh just switch to bash, which should be available on the hosts affected.

Link: https://www.shellcheck.net/wiki/SC3001
Fixes: 03dbd132eb ("🔊 Send DD24 cron errors to syslog")
Fixes: 38fbff30b5 ("feat: add role to manage dyndns entry on desec.io")

roles/dd24_dyndns_cron/templates/dd24-dyndns.cron.j2

@@ -1,6 +1,6 @@
 # /etc/cron.d/dd24-dyndns: Cron call to renew DynDNS entry
 
-SHELL=/bin/sh
+SHELL=/bin/bash
 PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
 
 */5 * * * * root curl --silent --show-error "https://dynamicdns.key-systems.net/update.php?hostname={{dyndns_domain}}&password={{dyndns_password}}&ip={{dyndns_ip}}" > /dev/null 2> >(/usr/bin/logger -p user.error -t dd24)

roles/desec_dyndns_cron/templates/desec-dyndns.cron.j2

@@ -1,6 +1,6 @@
 # /etc/cron.d/desec-dyndns: Cron call to renew DynDNS entry
 
-SHELL=/bin/sh
+SHELL=/bin/bash
 PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
 
 */5 * * * * root curl --silent --show-error --user {{ dyndns_domain }}:{{ dyndns_token }} "https://update.dedyn.io/" > /dev/null 2> >(/usr/bin/logger -p user.error -t desec)