Bump credo from 1.2.0 to 1.2.1 (#32)

Bumps [credo](https://github.com/rrrene/credo) from 1.2.0 to 1.2.1.
- [Release notes](https://github.com/rrrene/credo/releases)
- [Changelog](https://github.com/rrrene/credo/blob/master/CHANGELOG.md)
- [Commits](rrrene/credo@v1.2.0...v1.2.1)

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

mix.lock

@@ -1,7 +1,7 @@
 %{
   "bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [:mix], [], "hexpm"},
   "certifi": {:hex, :certifi, "2.5.1", "867ce347f7c7d78563450a18a6a28a8090331e77fa02380b4a21962a65d36ee5", [], [{:parse_trans, "~>3.3", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm"},
-  "credo": {:hex, :credo, "1.2.0", "a6a0020ea014ec0eb295c24e43ea24e2cf50b9f987a9ba86bb1f40816662e830", [:mix], [{:bunt, "~> 0.2.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm"},
+  "credo": {:hex, :credo, "1.2.1", "6d8e07b31e3937b669e19add0076ee9bd7268cf433878209b631fe38110ea94a", [:mix], [{:bunt, "~> 0.2.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm"},
   "dialyxir": {:hex, :dialyxir, "0.5.1", "b331b091720fd93e878137add264bac4f644e1ddae07a70bf7062c7862c4b952", [:mix], [], "hexpm"},
   "earmark": {:hex, :earmark, "1.3.5", "0db71c8290b5bc81cb0101a2a507a76dca659513984d683119ee722828b424f6", [:mix], [], "hexpm"},
   "ex_doc": {:hex, :ex_doc, "0.21.2", "caca5bc28ed7b3bdc0b662f8afe2bee1eedb5c3cf7b322feeeb7c6ebbde089d6", [:mix], [{:earmark, "~> 1.3.3 or ~> 1.4", [hex: :earmark, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm"},