Remove color check on test

failed locally in elixir <= 1.15
passed on CI because ansi colors are disabled

test/mix/tasks/compile/surface_test.exs

@@ -79,7 +79,7 @@ defmodule Mix.Tasks.Compile.SurfaceTest do
         assert {:ok, [^diagnostic]} = handle_diagnostics([diagnostic], [])
       end)
 
-    assert output =~ IO.ANSI.format([:yellow, "warning:"]) |> IO.iodata_to_binary()
+    assert output =~ "warning:"
     assert output =~ "test warning\n  file.ex:1: (file)\n\n"
   end