Update rubocop requirement from 1.81.1 to 1.81.7 (#209)

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@v1.81.1...v1.81.7)

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

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

Author: dependabot[bot]

Gemfile

@@ -6,7 +6,7 @@ gemspec
 gem "minitest", "~> 5.11"
 gem "minitest-rg", "~> 5.3"
 gem "rake", "~> 13.0"
-gem "rubocop", "1.81.1"
+gem "rubocop", "1.81.7"
 gem "rubocop-minitest", "0.38.2"
 gem "rubocop-packaging", "0.6.0"
 gem "rubocop-performance", "1.26.0"