Bump skylight from 3.1.5 to 4.0.1

Bumps [skylight](https://github.com/skylightio/skylight-ruby) from 3.1.5 to 4.0.1.
- [Release notes](https://github.com/skylightio/skylight-ruby/releases)
- [Changelog](https://github.com/skylightio/skylight-ruby/blob/master/CHANGELOG.md)
- [Commits](skylightio/skylight-ruby@v3.1.5...v4.0.1)

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

Gemfile.lock

@@ -322,9 +322,9 @@ GEM
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
-    skylight (3.1.5)
-      skylight-core (= 3.1.5)
-    skylight-core (3.1.5)
+    skylight (4.0.1)
+      skylight-core (= 4.0.1)
+    skylight-core (4.0.1)
       activesupport (>= 4.2.0)
     slim (4.0.1)
       temple (>= 0.7.6, < 0.9)