feat(deps): upgrade dependencies

* `decimal`: from 2.1.1 to 2.3.0
* `earmark_parser`: from 1.4.41 to 1.4.43
* `ex_doc`: from 0.34.2 to 0.36.1
* `req`: from 0.5.7 to 0.5.8

https://diff.hex.pm/diffs?diffs[]=decimal:2.1.1:2.3.0&diffs[]=earmark_parser:1.4.41:1.4.43&diffs[]=ex_doc:0.34.2:0.36.1&diffs[]=req:0.5.7:0.5.8&

mix.exs

@@ -35,12 +35,12 @@ defmodule Wabanex.MixProject do
        ref: "307c8bb14f9eec8a5cd77842366ac4eae7f17d76"},
       {:credo, "~> 1.7.0", only: [:dev, :test], runtime: false},
       {:crudry, "~> 2.4.0"},
-      {:decimal, "~> 2.1.0"},
+      {:decimal, "~> 2.3.0"},
       {:dialyxir, "~> 1.4.0", only: [:dev, :test], runtime: false},
       {:dns_cluster, "~> 0.1.1"},
       {:ecto_sql, "~> 3.12.0"},
       {:elixlsx, "~> 0.6.0", only: :test},
-      {:ex_doc, "~> 0.34.0", only: :dev, runtime: false},
+      {:ex_doc, "~> 0.36.0", only: :dev, runtime: false},
       {:gettext, "~> 0.26.0"},
       {:jason, "~> 1.4.0"},
       {:junit_formatter, "~> 3.4.0", only: [:test]},