Fix CI

Author: josevalim

lib/mix/test/mix/task_test.exs

@@ -43,7 +43,7 @@ defmodule Mix.TaskTest do
   end
 
   test "run/2 converts OptionParser.ParseError into Mix errors" do
-    message = "Could not invoke task \"hello\": 1 error found!\n--unknown : Unknown option"
+    message = ~r"Could not invoke task \"hello\": 1 error found!\n--unknown : Unknown option"
 
     assert_raise Mix.Error, message, fn ->
       Mix.Task.run("hello", ["--parser", "--unknown"])
@@ -52,7 +52,7 @@ defmodule Mix.TaskTest do
     Mix.Task.clear()
 
     message =
-      "Could not invoke task \"hello\": 1 error found!\n--int : Expected type integer, got \"foo\""
+      ~r"Could not invoke task \"hello\": 1 error found!\n--int : Expected type integer, got \"foo\""
 
     assert_raise Mix.Error, message, fn ->
       Mix.Task.run("hello", ["--parser", "--int", "foo"])