Update octokit requirement from >= 4.6, < 6.0 to >= 4.6, < 7.0

Updates the requirements on [octokit](https://github.com/octokit/octokit.rb) to permit the latest version.
- [Release notes](https://github.com/octokit/octokit.rb/releases)
- [Changelog](https://github.com/octokit/octokit.rb/blob/main/RELEASE.md)
- [Commits](octokit/octokit.rb@v4.6.0...v6.0.0)

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

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

Author: dependabot[bot]

common/dependabot-common.gemspec

@@ -31,7 +31,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency "faraday", "2.6.0"
   spec.add_dependency "gitlab", "4.19.0"
   spec.add_dependency "nokogiri", "~> 1.8"
-  spec.add_dependency "octokit", ">= 4.6", "< 6.0"
+  spec.add_dependency "octokit", ">= 4.6", "< 7.0"
   spec.add_dependency "parser", ">= 2.5", "< 4.0"
   spec.add_dependency "toml-rb", ">= 1.1.2", "< 3.0"