Update rubocop requirement from 0.52.1 to 1.8.1

Updates the requirements on [rubocop](https://github.com/rubocop-hq/rubocop) to permit the latest version.
- [Release notes](https://github.com/rubocop-hq/rubocop/releases)
- [Changelog](https://github.com/rubocop-hq/rubocop/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop@v0.52.1...v1.8.1)

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

Author: dependabot-preview[bot]

Gemfile

@@ -3,4 +3,4 @@ source "https://rubygems.org"
 # Specify your gem's dependencies in language_server.gemspec
 gemspec
 
-gem "rubocop", "0.52.1"
+gem "rubocop", "1.8.1"