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

@@ -32,7 +32,7 @@ group :test do
   gem 'govuk-content-schema-test-helpers', '~> 1.6.1'
   gem "rack-test", "~> 0.8.3"
   gem 'rspec'
-  gem "simplecov", "~> 0.15.1"
+  gem "simplecov", "~> 0.16.1"
   gem "simplecov-rcov", "~> 0.2.3"
   gem "timecop", "~> 0.9.1"
   gem "webmock", "~> 3.3.0"

Gemfile.lock

@@ -24,7 +24,7 @@ GEM
       safe_yaml (~> 1.0.0)
     crass (1.0.3)
     diff-lcs (1.3)
-    docile (1.1.5)
+    docile (1.3.0)
     domain_name (0.5.20170404)
       unf (>= 0.0.5, < 1.0.0)
     elasticsearch (2.0.2)
@@ -202,8 +202,8 @@ GEM
       activesupport
       sidekiq (>= 2.6)
       statsd-ruby (>= 1.1.0)
-    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)
@@ -262,7 +262,7 @@ DEPENDENCIES
   rake (~> 12.3)
   rspec
   sidekiq-limit_fetch
-  simplecov (~> 0.15.1)
+  simplecov (~> 0.16.1)
   simplecov-rcov (~> 0.2.3)
   sinatra (~> 2.0.1)
   statsd-ruby (~> 1.4.0)