chore(neovim): switch to ALE

The Asynchronous Lint Engine replaces the deprecated syntastic

profiles/neovim.nix

@@ -11,6 +11,7 @@
       configure = {
         packages.myPlugins = with pkgs.vimPlugins; {
           start = [
+            ale # Asynchronous Lint Engine
             deoplete-nvim # an extensible and asynchronous completion framework
             formatter-nvim # A format runner for neovim
             fugitive # Vim Git wrapper
@@ -26,7 +27,6 @@
             nvim-treesitter # configurations and abstraction layer for Neovim.
             onedarkpro-nvim # Dark and light themes for Neovim
             supertab # Allows you to use <Tab> for all your insert completion
-            syntastic # Syntax checking hacks
             vim-terraform # tab completion, syntax highlighting, indentation
             vim-terraform-completion
             vim-cue # Cue filetype plugin for Vim