Add castore dependency for CI

** (ExCoveralls.ReportUploadError) Failed to use any SSL certificates.
We didn't find the :castore library, and we couldn't use OS certificates
because that requires OTP 25 or later. If you want to use :castore,
please add

  {:castore, "~> 1.0"}

mix.exs

@@ -39,7 +39,8 @@ defmodule RemoteIp.Mixfile do
       {:plug, "~> 1.14"},
       {:ex_doc, "~> 0.34", only: :dev, runtime: false},
       {:dialyxir, "~> 1.4", only: [:ci, :dev], runtime: false},
-      {:excoveralls, "~> 0.18", only: [:ci, :test], runtime: false}
+      {:excoveralls, "~> 0.18", only: [:ci, :test], runtime: false},
+      {:castore, "~> 1.0", only: [:ci, :test], runtime: false}
     ]
   end
 

mix.lock

@@ -1,4 +1,5 @@
 %{
+  "castore": {:hex, :castore, "1.0.7", "b651241514e5f6956028147fe6637f7ac13802537e895a724f90bf3e36ddd1dd", [:mix], [], "hexpm", "da7785a4b0d2a021cd1292a60875a784b6caef71e76bf4917bdee1f390455cf5"},
   "combine": {:hex, :combine, "0.10.0", "eff8224eeb56498a2af13011d142c5e7997a80c8f5b97c499f84c841032e429f", [:mix], [], "hexpm", "1b1dbc1790073076580d0d1d64e42eae2366583e7aecd455d1215b0d16f2451b"},
   "dialyxir": {:hex, :dialyxir, "1.4.3", "edd0124f358f0b9e95bfe53a9fcf806d615d8f838e2202a9f430d59566b6b53b", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "bf2cfb75cd5c5006bec30141b131663299c661a864ec7fbbc72dfa557487a986"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.39", "424642f8335b05bb9eb611aa1564c148a8ee35c9c8a8bba6e129d51a3e3c6769", [:mix], [], "hexpm", "06553a88d1f1846da9ef066b87b57c6f605552cfbe40d20bd8d59cc6bde41944"},