This is so that we can do simple changes to the docker images
in provisioning, without needing to update the tag here.
If a backwards-incompatible change in the docker images needs to be committed
in provisioning and here, it is possible because the images retain their old
unique SHA1 tag, in addition to being tagged as latest. See comment for more
details.
Requires the change in qt5 repository, with commit sha:
e4f9ac5607a329bae045567a339d36469bc4fff6
Task-number: QTBUG-79867
Change-Id: I1bc72edec62487530575d7e113a25afe16d09129
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
75f75e997a