Update ffi requirement from >= 1.15.5, < 1.17.0, != 1.16.0, != 1.16.1, != 1.16.2 to >= 1.15.5, != 1.16.0, != 1.16.1, != 1.16.2, < 1.18.0

Updates the requirements on [ffi](https://github.com/ffi/ffi) to permit the latest version.
- [Changelog](https://github.com/ffi/ffi/blob/master/CHANGELOG.md)
- [Commits](ffi/ffi@v1.15.5...v1.17.2)

---
updated-dependencies:
- dependency-name: ffi
  dependency-version: 1.17.2
  dependency-type: direct:development
...

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

Author: dependabot[bot]

Gemfile

@@ -41,7 +41,7 @@ end
 
 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 'ffi', '>= 1.15.5', '!= 1.16.0', '!= 1.16.1', '!= 1.16.2', '< 1.18.0', require: false
   gem "json-schema", '>= 2', '< 6', require: false
   gem "rake", *location_for(ENV['RAKE_LOCATION'] || '~> 13.0')
   gem "rspec", "~> 3.1", require: false