Bump simplecov from 0.15.1 to 0.16.1

Bumps [simplecov](https://github.com/colszowka/simplecov) from 0.15.1 to 0.16.1.
- [Release notes](https://github.com/colszowka/simplecov/releases)
- [Changelog](https://github.com/colszowka/simplecov/blob/master/CHANGELOG.md)
- [Commits](simplecov-ruby/simplecov@v0.15.1...v0.16.1)

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

Gemfile.lock

@@ -90,7 +90,7 @@ GEM
       thor
     crass (1.0.4)
     diff-lcs (1.3)
-    docile (1.1.5)
+    docile (1.3.0)
     domain_name (0.5.20170404)
       unf (>= 0.0.5, < 1.0.0)
     erubi (1.7.0)
@@ -225,8 +225,8 @@ GEM
     selenium-webdriver (3.8.0)
       childprocess (~> 0.5)
       rubyzip (~> 1.0)
-    simplecov (0.15.1)
-      docile (~> 1.1.0)
+    simplecov (0.16.1)
+      docile (~> 1.1)
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)