chore(deps): update appium_lib_core requirement from >= 5, < 8 to >= 5, < 9 (#666)

Updates the requirements on [appium_lib_core](https://github.com/appium/ruby_lib_core) to permit the latest version.
- [Changelog](https://github.com/appium/ruby_lib_core/blob/master/CHANGELOG.md)
- [Commits](appium/ruby_lib_core@v5.0.0...v8.0.0)

---
updated-dependencies:
- dependency-name: appium_lib_core
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

finder/ruby/appium_flutter_finder.gemspec

@@ -23,7 +23,7 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ['lib']
 
-  spec.add_runtime_dependency 'appium_lib_core', '>= 5', '< 8'
+  spec.add_runtime_dependency 'appium_lib_core', '>= 5', '< 9'
 
   spec.add_development_dependency 'bundler', '>= 1.17'
   spec.add_development_dependency 'minitest', '~> 5.0'