mod_s2s_keepalive: Fix identification of replies (error-replies included) Typo? This condition is supposed to filter out get and set (and anything else), not errors, which can still mean that there's connectivity, just no handling of XEP-0199.

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summary: Log a message once per minute
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This module sends `-- MARK --` to the log once per minute. This may be
useful to give a sense of how busy the server is or see that logging and
timers are still working.