CI: use kerl/linuxbrew to install specific erlang versions

[andreineculau]

see https://github.com/for-GET/jesse/pull/98#issuecomment-755029967

to clarify: we should be able to test with any desired erlang version, including those disabled in https://github.com/for-GET/jesse/commit/dfe93481e76e1077c5e778034a522a99a45152bd#diff-b803fcb7f17ed9235f1e5cb1fcd2f5d3b2838429d4368ae4c57ce4436577f03f

FWIW I see kerl supports only 20+ https://github.com/kerl/kerl#otp-support-policy

[andreineculau]

reverted using kerl, because it takes e.g. 13 minutes to install an erlang version. seems a waste even for the CI...

for summary:

• we need git 2.18+ because of how actions/checkout@v2 is written (could be changed not to need 2.18 for the sake of using git protocol v2)
• we cannot get 2.18+ installed on debian jessie (which some erlang containers are based on) without errors, not from backports, not from contrib, not from source
• kerl seems fine, but it takes a long time. I guess caching would be an option.

Another option is to stop caring about the old erlang containers based on jessie. I'm putting a stop to this time consuming task, which was nice-to-have sorry to say (travis seems to work still).

I leave it up to you @paulo-ferraz-oliveira to come up with the best alternative in a PR, since you opened up pandora's box 😉.

[paulo-ferraz-oliveira]

Is the goal to just allow testing with any given OTP version? I'd propose dropping older versions, e.g pre OTP 19, to start with. (I think 5 years support is good enough!) But I can test with the https://github.com/marketplace/actions/setup-erlang action, let me open a draft pull request.

[paulo-ferraz-oliveira]

I got it running with almost all previous versions (less 18.1 and 18.2), for which I get the same stupid issue you do. I believe the rebar3 version packed with that failing container might be error'ing out.