ASN Lookup Database Check: "older than one week" but is newer

[sebix]

The newly introduced (#2606) check does not work as intended:

Bot 'asnlookup-expert': Database (/var/lib/intelmq/bots/asn_lookup/ipasn.dat) is older than one week. Check the auto update, see: https://docs.intelmq.org/latest/user/bots/#asn-lookup.

But the file is not a week old:

$ ls -l /var/lib/intelmq/bots/asn_lookup/ipasn.dat
-rw-rw-r-- 1 intelmq intelmq 28731743 Jul 29 20:06 /var/lib/intelmq/bots/asn_lookup/ipasn.dat