Bump cors_plug from 1.5.2 to 2.0.0

Bumps [cors_plug](https://github.com/mschae/cors_plug) from 1.5.2 to 2.0.0.
- [Release notes](https://github.com/mschae/cors_plug/releases)
- [Changelog](https://github.com/mschae/cors_plug/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mschae/cors_plug/compare/v1.5.2...v2.0.0)

mix.exs

@@ -60,7 +60,7 @@ defmodule Mobilizon.Mixfile do
       {:guardian_db, "~> 1.1"},
       {:comeonin, "~> 4.0"},
       {:argon2_elixir, "~> 1.2"},
-      {:cors_plug, "~> 1.2"},
+      {:cors_plug, "~> 2.0"},
       {:ecto_autoslug_field, "~> 0.3"},
       {:rsa_ex, "~> 0.1"},
       {:geo, "~> 3.0"},