Update simplecov requirement to ~> 0.16.1 (#8)

Updates the requirements on [simplecov](https://github.com/colszowka/simplecov) to permit the latest version.
- [Release notes](https://github.com/colszowka/simplecov/releases)
- [Changelog](https://github.com/colszowka/simplecov/blob/master/CHANGELOG.md)
- [Commits](simplecov-ruby/simplecov@v0.13.0...v0.16.1)

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

Gemfile.lock

@@ -10,7 +10,7 @@ GEM
     ast (2.4.0)
     dentaku (3.2.0)
     diff-lcs (1.3)
-    docile (1.1.5)
+    docile (1.3.0)
     json (2.1.0)
     parallel (1.12.1)
     parser (2.4.0.2)
@@ -39,8 +39,8 @@ GEM
       ruby-progressbar (~> 1.7)
       unicode-display_width (~> 1.0, >= 1.0.1)
     ruby-progressbar (1.9.0)
-    simplecov (0.13.0)
-      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)
@@ -55,7 +55,7 @@ DEPENDENCIES
   rake (~> 12.0)
   rspec (~> 3.5)
   rubocop (~> 0.52)
-  simplecov (~> 0.13.0)
+  simplecov (~> 0.16.1)
   yard (~> 0.9)
 
 BUNDLED WITH

memory_io.gemspec

@@ -25,6 +25,6 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rake', '~> 12.0'
   s.add_development_dependency 'rspec', '~> 3.5'
   s.add_development_dependency 'rubocop', '~> 0.52'
-  s.add_development_dependency 'simplecov', '~> 0.13.0'
+  s.add_development_dependency 'simplecov', '~> 0.16.1'
   s.add_development_dependency 'yard', '~> 0.9'
 end