Fix issues on `symlink_to_last_ct_logs/1`
Fix issues on `symlink_to_last_ct_logs/1`

Now it should work in Erlang/OTP versions earlier than 20 and
update the symlink in case of one already existing (so that `last`
always points to the last run).

tsloughter/rebar3,rebar/rebar3,erlang/rebar3,rebar/rebar3,lrascao/rebar3,vladdu/rebar3,saleyn/rebar3