Bump excoveralls from 0.18.0 to 0.18.1

Bumps [excoveralls](https://github.com/parroty/excoveralls) from 0.18.0 to 0.18.1.
- [Release notes](https://github.com/parroty/excoveralls/releases)
- [Changelog](https://github.com/parroty/excoveralls/blob/master/CHANGELOG.md)
- [Commits](parroty/excoveralls@v0.18.0...v0.18.1)

---
updated-dependencies:
- dependency-name: excoveralls
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

mix.lock

@@ -8,7 +8,7 @@
   "earmark_parser": {:hex, :earmark_parser, "1.4.39", "424642f8335b05bb9eb611aa1564c148a8ee35c9c8a8bba6e129d51a3e3c6769", [:mix], [], "hexpm", "06553a88d1f1846da9ef066b87b57c6f605552cfbe40d20bd8d59cc6bde41944"},
   "erlex": {:hex, :erlex, "0.2.6", "c7987d15e899c7a2f34f5420d2a2ea0d659682c06ac607572df55a43753aa12e", [:mix], [], "hexpm", "2ed2e25711feb44d52b17d2780eabf998452f6efda104877a3881c2f8c0c0c75"},
   "ex_doc": {:hex, :ex_doc, "0.32.1", "21e40f939515373bcdc9cffe65f3b3543f05015ac6c3d01d991874129d173420", [:mix], [{:earmark_parser, "~> 1.4.39", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_c, ">= 0.1.1", [hex: :makeup_c, repo: "hexpm", optional: true]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1", [hex: :makeup_erlang, repo: "hexpm", optional: false]}], "hexpm", "5142c9db521f106d61ff33250f779807ed2a88620e472ac95dc7d59c380113da"},
-  "excoveralls": {:hex, :excoveralls, "0.18.0", "b92497e69465dc51bc37a6422226ee690ab437e4c06877e836f1c18daeb35da9", [:mix], [{:castore, "~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "1109bb911f3cb583401760be49c02cbbd16aed66ea9509fc5479335d284da60b"},
+  "excoveralls": {:hex, :excoveralls, "0.18.1", "a6f547570c6b24ec13f122a5634833a063aec49218f6fff27de9df693a15588c", [:mix], [{:castore, "~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "d65f79db146bb20399f23046015974de0079668b9abb2f5aac074d078da60b8d"},
   "expo": {:hex, :expo, "0.5.2", "beba786aab8e3c5431813d7a44b828e7b922bfa431d6bfbada0904535342efe2", [:mix], [], "hexpm", "8c9bfa06ca017c9cb4020fabe980bc7fdb1aaec059fd004c2ab3bff03b1c599c"},
   "file_system": {:hex, :file_system, "1.0.0", "b689cc7dcee665f774de94b5a832e578bd7963c8e637ef940cd44327db7de2cd", [:mix], [], "hexpm", "6752092d66aec5a10e662aefeed8ddb9531d79db0bc145bb8c40325ca1d8536d"},
   "floki": {:hex, :floki, "0.36.1", "712b7f2ba19a4d5a47dfe3e74d81876c95bbcbee44fe551f0af3d2a388abb3da", [:mix], [], "hexpm", "21ba57abb8204bcc70c439b423fc0dd9f0286de67dc82773a14b0200ada0995f"},