Revert "Add certifi"

This reverts commit 446c25c.

mix.exs

@@ -76,7 +76,6 @@ defmodule RDF.Mixfile do
       {:excoveralls, "~> 0.18", only: :test},
       # This dependency is needed for ExCoveralls when OTP < 25
       {:castore, "~> 1.0", only: :test},
-      {:certifi, "~> 2.13", only: :test},
       {:benchee, "~> 1.3", only: :dev}
     ]
   end

mix.lock

@@ -2,7 +2,6 @@
   "benchee": {:hex, :benchee, "1.3.0", "f64e3b64ad3563fa9838146ddefb2d2f94cf5b473bdfd63f5ca4d0657bf96694", [:mix], [{:deep_merge, "~> 1.0", [hex: :deep_merge, repo: "hexpm", optional: false]}, {:statistex, "~> 1.0", [hex: :statistex, repo: "hexpm", optional: false]}, {:table, "~> 0.1.0", [hex: :table, repo: "hexpm", optional: true]}], "hexpm", "34f4294068c11b2bd2ebf2c59aac9c7da26ffa0068afdf3419f1b176e16c5f81"},
   "bunt": {:hex, :bunt, "1.0.0", "081c2c665f086849e6d57900292b3a161727ab40431219529f13c4ddcf3e7a44", [:mix], [], "hexpm", "dc5f86aa08a5f6fa6b8096f0735c4e76d54ae5c9fa2c143e5a1fc7c1cd9bb6b5"},
   "castore": {:hex, :castore, "1.0.7", "b651241514e5f6956028147fe6637f7ac13802537e895a724f90bf3e36ddd1dd", [:mix], [], "hexpm", "da7785a4b0d2a021cd1292a60875a784b6caef71e76bf4917bdee1f390455cf5"},
-  "certifi": {:hex, :certifi, "2.13.0", "e52be248590050b2dd33b0bb274b56678f9068e67805dca8aa8b1ccdb016bbf6", [:rebar3], [], "hexpm", "8f3d9533a0f06070afdfd5d596b32e21c6580667a492891851b0e2737bc507a1"},
   "credo": {:hex, :credo, "1.7.5", "643213503b1c766ec0496d828c90c424471ea54da77c8a168c725686377b9545", [:mix], [{:bunt, "~> 0.2.1 or ~> 1.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:file_system, "~> 0.2 or ~> 1.0", [hex: :file_system, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "f799e9b5cd1891577d8c773d245668aa74a2fcd15eb277f51a0131690ebfb3fd"},
   "decimal": {:hex, :decimal, "2.1.1", "5611dca5d4b2c3dd497dec8f68751f1f1a54755e8ed2a966c2633cf885973ad6", [:mix], [], "hexpm", "53cfe5f497ed0e7771ae1a475575603d77425099ba5faef9394932b35020ffcc"},
   "deep_merge": {:hex, :deep_merge, "1.0.0", "b4aa1a0d1acac393bdf38b2291af38cb1d4a52806cf7a4906f718e1feb5ee961", [:mix], [], "hexpm", "ce708e5f094b9cd4e8f2be4f00d2f4250c4095be93f8cd6d018c753894885430"},