fix: update 404 error message

Author: zcesur

test/algora_web/controllers/error_html_test.exs

@@ -5,7 +5,7 @@ defmodule AlgoraWeb.ErrorHTMLTest do
   import Phoenix.Template
 
   test "renders 404.html" do
-    assert render_to_string(AlgoraWeb.ErrorHTML, "404", "html", []) == "Not Found"
+    assert render_to_string(AlgoraWeb.ErrorHTML, "404", "html", []) =~ "could not be found"
   end
 
   test "renders 500.html" do