WIP: test fixes (#352)

After a lot of debugging, I believe that issue that was ailing our test suite was a compiler deadlock that manifested in Erlang 23 https://bugs.erlang.org/browse/ERL-1236
So simply upgrading the erlang version resolved the issue.

Author: axelson

.travis.yml

@@ -23,7 +23,7 @@ matrix:
       elixir: 1.8.2
     - otp_release: 22.3
       elixir: 1.9.4
-    - otp_release: 23.0
+    - otp_release: 23.0.3
       elixir: 1.10.3
       env:
         - CHECK_FORMATTED=1

CHANGELOG.md

@@ -20,6 +20,7 @@ House keeping:
 - Add vim-lsp to plugin list (thanks [Thanabodee Charoenpiriyakij](https://github.com/wingyplus)) [#340](https://github.com/elixir-lsp/elixir-ls/pull/340)
 - Cleanup test output (thanks [Jason Axelson](https://github.com/axelson)) [#347](https://github.com/elixir-lsp/elixir-ls/pull/347)
 - Remove the default .tool-versions file (thanks [Jason Axelson](https://github.com/axelson)) [#351](https://github.com/elixir-lsp/elixir-ls/pull/351)
+- Fix up the test suite (thanks [Jason Axelson](https://github.com/axelson)) [#352](https://github.com/elixir-lsp/elixir-ls/pull/352)
 
 Note: `MIX_TARGET` support was added in 0.5.0 but wasn't added to the changelog until later:
 - Support `MIX_TARGET` so the language server can have target specific contexts, like with Nerves (thanks [Jon Carstens](https://github.com/jjcarstens)) [#299](https://github.com/elixir-lsp/elixir-ls/pull/299)