fix build on elixir 1.11

Author: lukaszsamson

apps/language_server/lib/language_server/providers/completion.ex

@@ -326,7 +326,7 @@ defmodule ElixirLS.LanguageServer.Providers.Completion do
       Atom.to_string(required_alias)
       |> String.replace_prefix("Elixir.", "")
 
-    indentation = 1..column_to_insert_alias//1 |> Enum.map(fn _ -> " " end) |> Enum.join()
+    indentation = 1..column_to_insert_alias |> Enum.map(fn _ -> " " end) |> Enum.join()
     alias_edit = indentation <> "alias " <> alias_value <> "\n"
 
     struct(completion_without_additional_text_edit,