Update simplecov-html requirement from ~> 0.12.3 to ~> 0.13.1

Updates the requirements on [simplecov-html](https://github.com/simplecov-ruby/simplecov-html) to permit the latest version.
- [Release notes](https://github.com/simplecov-ruby/simplecov-html/releases)
- [Changelog](https://github.com/simplecov-ruby/simplecov-html/blob/main/CHANGELOG.md)
- [Commits](simplecov-ruby/simplecov-html@v0.12.3...v0.13.1)

---
updated-dependencies:
- dependency-name: simplecov-html
  dependency-type: direct:development
...

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

oxidized.gemspec

@@ -44,5 +44,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rubocop-rake',        '~> 0.6.0'
   s.add_development_dependency 'simplecov',           '~> 0.22.0'
   s.add_development_dependency 'simplecov-cobertura', '~> 2.1.0'
-  s.add_development_dependency 'simplecov-html',      '~> 0.12.3'
+  s.add_development_dependency 'simplecov-html',      '~> 0.13.1'
 end