The current version of actions/checkout is v3. That means that v2, which
we currently use, has been superseded. Update the version we use
accordingly.
Signed-off-by: Daniel Müller <deso@posteo.net>
github action grouping is broken because we were outputing "::endgroup" where
it needs "::endgroup::". This patch also added some addtional grouping around
contianer setup phase, making output easier to read.