Update racc requirement from 1.5.2 to 1.8.1

Updates the requirements on [racc](https://github.com/ruby/racc) to permit the latest version.
- [Release notes](https://github.com/ruby/racc/releases)
- [Changelog](https://github.com/ruby/racc/blob/master/ChangeLog)
- [Commits](ruby/racc@v1.5.2...v1.8.1)

---
updated-dependencies:
- dependency-name: racc
  dependency-version: 1.8.1
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Gemfile

@@ -45,7 +45,7 @@ group(:test) do
   # 1.16.0 - 1.16.2 are broken on Windows
   gem 'ffi', '>= 1.15.5', '< 1.17.0', '!= 1.16.0', '!= 1.16.1', '!= 1.16.2', require: false
   gem "json-schema", "~> 2.0", require: false
-  gem "racc", "1.5.2", require: false
+  gem "racc", "1.8.1", require: false
   gem "rake", *location_for(ENV['RAKE_LOCATION'] || '~> 13.0')
   gem "rspec", "~> 3.1", require: false
   gem "rspec-expectations", ["~> 3.9", "!= 3.9.3"]