Bump guardian from 1.2.1 to 2.0.0

Bumps [guardian](https://github.com/ueberauth/guardian) from 1.2.1 to 2.0.0.
- [Release notes](https://github.com/ueberauth/guardian/releases)
- [Changelog](https://github.com/ueberauth/guardian/blob/master/CHANGELOG.md)
- [Commits](ueberauth/guardian@v1.2.1...v2.0.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

mix.exs

@@ -48,7 +48,7 @@ defmodule OpensourceChallenge.Mixfile do
       {:ja_serializer, "~> 0.15.0"},
       {:ja_resource, "~> 0.3.0"},
       {:bcrypt_elixir, "~> 2.0"},
-      {:guardian, "~> 1.2.1"},
+      {:guardian, "~> 2.0.0"},
       {:canada, "~> 2.0.0", override: true},
       {:canary, "~> 1.1.0"},
       {:gettext, "~> 0.11"},

mix.lock

@@ -17,7 +17,7 @@
   "elixir_make": {:hex, :elixir_make, "0.5.2", "96a28c79f5b8d34879cd95ebc04d2a0d678cfbbd3e74c43cb63a76adf0ee8054", [:mix], [], "hexpm"},
   "elixir_uuid": {:hex, :elixir_uuid, "1.2.0", "ff26e938f95830b1db152cb6e594d711c10c02c6391236900ddd070a6b01271d", [:mix], [], "hexpm"},
   "gettext": {:hex, :gettext, "0.17.1", "8baab33482df4907b3eae22f719da492cee3981a26e649b9c2be1c0192616962", [:mix], [], "hexpm"},
-  "guardian": {:hex, :guardian, "1.2.1", "bdc8dd3dbf0fb7216cb6f91c11831faa1a64d39cdaed9a611e37f2413e584983", [:mix], [{:jose, "~> 1.8", [hex: :jose, repo: "hexpm", optional: false]}, {:phoenix, "~> 1.3", [hex: :phoenix, repo: "hexpm", optional: true]}, {:plug, "~> 1.3.3 or ~> 1.4", [hex: :plug, repo: "hexpm", optional: true]}], "hexpm"},
+  "guardian": {:hex, :guardian, "2.0.0", "5d3e537832b7cf35c8674da92457b7be671666a2eff4bf0f2ccfcfb3a8c67a0b", [:mix], [{:jose, "~> 1.8", [hex: :jose, repo: "hexpm", optional: false]}, {:plug, "~> 1.3.3 or ~> 1.4", [hex: :plug, repo: "hexpm", optional: true]}], "hexpm"},
   "hackney": {:hex, :hackney, "1.15.1", "9f8f471c844b8ce395f7b6d8398139e26ddca9ebc171a8b91342ee15a19963f4", [:rebar3], [{:certifi, "2.5.1", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "6.0.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "~>1.1", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.4", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm"},
   "httpoison": {:hex, :httpoison, "0.10.0", "4727b3a5e57e9a4ff168a3c2883e20f1208103a41bccc4754f15a9366f49b676", [:mix], [{:hackney, "~> 1.6.3", [hex: :hackney, optional: false]}]},
   "idna": {:hex, :idna, "6.0.0", "689c46cbcdf3524c44d5f3dde8001f364cd7608a99556d8fbd8239a5798d4c10", [:rebar3], [{:unicode_util_compat, "0.4.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm"},