Update to Elixir 1.19

[angelikatyborska]

Before merging, exercism/elixir#1603 needs to be merged and pulled here.

[angelikatyborska]

Something is for sure wrong with the unit tests of exercism_test_helper, many tests hang for a longer time and then timeout.

[angelikatyborska]

Turns out it was exactly the same thing as in my library: angelikatyborska/doctest_formatter#48

Inspect.Algebra.format started returning strings sometimes. It's supposed to return io_data, which is a string or list of strings, but in the past it always returned a list of strings. Now that it returns strings, it caused an infinite loop where the clause of colorize that calls itself would always match, because is_doc is true for a string, but not for a list of strings. Infinite loop = hanging test.

[jiegillet]

Not sure why it's still in draft, but it looks good to me now.

[angelikatyborska]

It was still in draft because I was waiting for exercism/elixir-analyzer#457 to be fully passing. All tooling should get merged at the same time.

[angelikatyborska]

@jiegillet 1.19.4 broke one smoke test and I cannot figure out how to change it so that is passes both locally and on CI 😵