ci: use Docker image with libknot 2.7

9 jobs for ci_fix in 1 minute and 43 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #166071
amd64 linux docker
test:augeas

00:00:57

passed #166076
amd64 linux docker
test:comparative:kresd

00:01:43

passed #166077
amd64 linux docker
test:latest:kresd

00:01:00

passed #166072
amd64 linux docker
test:pep8

00:00:52

passed #166073
amd64 linux docker
test:pylint

00:00:31

passed #166074
amd64 linux docker
test:rplint

00:00:51

passed #166079
amd64 linux docker
test:sanity:pdnsrecursor

00:00:30

passed #166078
amd64 linux docker
test:sanity:unbound

00:00:59

passed #166075
amd64 linux docker
test:unittests

00:00:23