fix #3651

Similar to Jinja, getting `eex` highlighting in *.ex files
will require users to setup a filetype hook similar to the
following:

hook global WinSetOption filetype=elixir %{
    require-module eex
    add-highlighter window/eex ref eex
}

This is done both to fix a circular dependency between the `elixir`
and `eex` modules, and avoid polluting `elixir` files with false
positives from `eex` highlighting given `eex` is framework specific

rc/filetype/elixir.kak

@@ -52,7 +52,6 @@ add-highlighter shared/eex/code region '<%=?' '%>' ref elixir
 }
 
 provide-module elixir %[
-require-module eex
 
 # Highlighters
 # ‾‾‾‾‾‾‾‾‾‾‾‾