docker :latest should point to master not latest PR build

[yarikoptic]

ATM

so running :latest would result running that PR image.

Ideally, IMHO, :latest should correspond to "latest release" but there seems to be no releases really (and :master to last build on master branch -- all consistent and clear). But it better not to point to some PR (could still be buggy/breaking/etc).

edit 1: it seems to be not quite trivial to filter through all those tags and find commit- tag on docker hub corresponding to master, just need to do it "manually" from looking at commit of current master:

❯ pwd
/home/yoh/proj/misc/qlever
❯ docker pull adfreiburg/qlever:commit-$(git log -1 --format="%h")
commit-e3dcc9c: Pulling from adfreiburg/qlever
7646c8da3324: Pulling fs layer 
...