Because `master` branch seems incompatible, or at least with breaking
changes that cause the test to fail.

Because that's the minimum required by hexpm server.

- Update expected cowlib version in core-query tests
- Add -k flag to lockf in core/deps.mk to prevent concurrency issues
during rebar3 bootstra

This will ensure we properly rebuild projects that have
a .app file committed, since the .d file is not.

Thanks Ilya Khaprov for the fix.

This is the same as `check`. The files of the cross-platform-actions VM
are synchronised in both ways, so we can re-use the same configuration.

`vmactions` VM fails to boot quite frequently and we have no visibility
on the reason of the failure.

The only failure I got out-of-the-box with cross-platform-actions VM was
the `core-deps-rel` test case which hangs. It comes from the use of
`erl_call` to detect if the Erlang node was started correctly. A comment
in the generated release starts scripts says:

    # users who depend on stdout when running rpc calls must still use nodetool
    # so we have an overload option to force use of nodetool instead of erl_call

If `$USE_NODETOOL` is set, it will use `relx_nodetool` instead. Indeed,
this fixed the hang.