Some maintenance updates (#62)

* Move test-specific rebar.config options to the test profile

* Trim .gitignore to bare requirements for a rebar3 project

* Update some CI versions

* Tweak dialyzer options

* underspecs allows for stricts typespecs, which is good
* no_return prevents a class of warnings we might want to be aware of

* Analyse it with XRef

* markdownlint it!

* YAMLlint it!

* Prefer ex_doc to EDoc

Also adds a much-deserved badge to README.md

* Analyse further

We also add `no_unknown` to Dialyzer (because `unknown` is
default in OTP 26), so we can fix errors locally without having to
wait for CI (if locally you're using OTP 25, and CI fails in OTP 26,
that is)

* Fix as per CI: Warning: ... is undefined function (Xref)

Fix #52: Handle new format for HEX responses (#53)

Add more dialyzer checks (#51)

* Add more dialyzer checks

* Recover unmatched_returns

[AUTO] [ RTI-13369 ] Update Dependencies (#46)

* Update dependencies

* Adjust to new hex_core format

Co-authored-by: Brujo Benavides Rodriguez <elbrujohalcon@gmail.com>

Fix recent change that broke the git command (#38)

Add proper sorting to git ls-remote (#37)

* Add proper sorting to git ls-remote

* Format

* Remove unneeded pieces

Improve on previous fix (#32)

Output (visible) message in case of error (#31)

Handle unicode in rebar.config (#25)

Remove dep check. It was too unstable (#24)