Bump credo from 0.8.10 to 0.9.1

Bumps [credo](https://github.com/rrrene/credo) from 0.8.10 to 0.9.1.
- [Release notes](https://github.com/rrrene/credo/releases)
- [Changelog](https://github.com/rrrene/credo/blob/master/CHANGELOG.md)
- [Commits](rrrene/credo@v0.8.10...v0.9.1)

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

mix.lock

@@ -1,7 +1,7 @@
 %{"bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [], [], "hexpm"},
   "certifi": {:hex, :certifi, "2.0.0", "a0c0e475107135f76b8c1d5bc7efb33cd3815cb3cf3dea7aefdd174dabead064", [], [], "hexpm"},
   "coverex": {:hex, :coverex, "1.4.15", "60fadf825a6c0439b79d1f98cdb54b6733cdd5cb1b35d15d56026c44ed15a5a8", [], [{:hackney, "~> 1.5", [hex: :hackney, repo: "hexpm", optional: false]}, {:poison, "~> 1.5 or ~> 2.0 or ~> 3.0", [hex: :poison, repo: "hexpm", optional: false]}], "hexpm"},
-  "credo": {:hex, :credo, "0.8.10", "261862bb7363247762e1063713bb85df2bbd84af8d8610d1272cd9c1943bba63", [:mix], [{:bunt, "~> 0.2.0", [hex: :bunt, repo: "hexpm", optional: false]}], "hexpm"},
+  "credo": {:hex, :credo, "0.9.1", "f021affa11b32a94dc2e807a6472ce0914289c9132f99644a97fc84432b202a1", [:mix], [{:bunt, "~> 0.2.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:poison, ">= 0.0.0", [hex: :poison, repo: "hexpm", optional: false]}], "hexpm"},
   "earmark": {:hex, :earmark, "1.2.4", "99b637c62a4d65a20a9fb674b8cffb8baa771c04605a80c911c4418c69b75439", [:mix], [], "hexpm"},
   "ex_doc": {:hex, :ex_doc, "0.18.3", "f4b0e4a2ec6f333dccf761838a4b253d75e11f714b85ae271c9ae361367897b7", [:mix], [{:earmark, "~> 1.1", [hex: :earmark, repo: "hexpm", optional: false]}], "hexpm"},
   "excoveralls": {:hex, :excoveralls, "0.8.1", "0bbf67f22c7dbf7503981d21a5eef5db8bbc3cb86e70d3798e8c802c74fa5e27", [:mix], [{:exjsx, ">= 3.0.0", [hex: :exjsx, repo: "hexpm", optional: false]}, {:hackney, ">= 0.12.0", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm"},