Update rubocop requirement from = 1.75.6 to = 1.81.7

Updates the requirements on [rubocop](https://github.com/rubocop/rubocop) to permit the latest version.
- [Release notes](https://github.com/rubocop/rubocop/releases)
- [Changelog](https://github.com/rubocop/rubocop/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop@v1.75.6...v1.81.7)

---
updated-dependencies:
- dependency-name: rubocop
  dependency-version: 1.81.7
  dependency-type: direct:production
...

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

Author: dependabot[bot]

panolint-ruby.gemspec

@@ -19,7 +19,7 @@ Gem::Specification.new do |spec|
 
   # Pinned to latest versions and will be updated by Dependabot
   # so that code bases using panolint-ruby will get the latest versions
-  spec.add_dependency "rubocop", "1.75.6"
+  spec.add_dependency "rubocop", "1.81.7"
   spec.add_dependency "rubocop-performance", "1.25.0"
   spec.add_dependency "rubocop-rspec", "3.6.0"
 end