Anticipate bump of Clamav to 1.3.1-r0 that will come with next Alpine release 3.21 in November

[borrelm]

Hello !

Based on their release cycle, Alpine will release the edge branch into 3.21 in November.
Edge branch bump clamav from 1.2.2-r0 to 1.3.1-r0

I don't have the skills to do it myself, but It would be nice if someone could test there is no regression in clamav-rest with clamav 1.3.1-r0 before then :)