Replace Travis-CI with GitHub Actions in this Project

[nelsonic]

We've been using GitHub Actions CI for all of our Elixir projects for a while ...
We should:

• update this repo to use Actions instead of Travis-CI

[nelsonic]

Opened this what feels like ages ago. ⏳ 🙄
Going to pick it off the backlog 🧑‍💻
so that we have a GOTO reference for our Elixir Projects. ✅

[nelsonic]

Trying to add some tests for the /examples but getting the following error:

==> ssl_verify_fun
Compiling 7 files (.erl)
src/ssl_verify_hostname.erl:16:14: can't find include lib "public_key/include/public_key.hrl"
%   16| -include_lib("public_key/include/public_key.hrl").
%     |              ^

Didn't know I needed ssl_verify_fun just to run some tests ... 🤷‍♂️

[nelsonic]

Followed: https://elixirforum.com/t/cannot-compile-ssl-verify-fun-in-windows-11/57265
Did:

rm mix.lock
mix deps.update --all
mix deps.get

Now have:

==> codecov_example
Generated codecov_example app
** (Mix) Cannot run tests because test helper file "test/test_helper.exs" does not exist

Easily solved:

echo "ExUnit.start()" >> test/test_helper.exs