Update Koha GITREF
Update Koha GITREF

In order to benefit from recent Plack and cache-related fixes.

digibib/koha-salt-docker,digibib/koha-docker,digibib/koha-salt-docker,digibib/koha-docker,digibib/koha-salt-docker,digibib/koha-salt-docker,digibib/koha-docker,digibib/koha-docker,digibib/koha-salt-docker,digibib/koha-docker,digibib/koha-docker