Update ruby dependencies

[dshevtsov]

This pull request focuses on maintenance and dependency upgrades, as well as improvements to CI workflows and linting configuration. The key updates are upgrading dependencies to their latest compatible versions, updating the changelog and version, and modernizing GitHub Actions workflows for testing and linting.

Dependency and version updates:

• Upgraded octokit dependency from ~> 8.0 to ~> 10.0 and cucumber from ~> 9.1 to ~> 10.1 in whatsup_github.gemspec, along with updates to other dependencies.
• Updated the project version to 1.2.0 in lib/whatsup_github/version.rb.
• Added a new entry for version 1.2.0 in CHANGELOG.md summarizing the maintenance and upgrade changes.

CI workflow and linting improvements:

• Updated GitHub Actions workflows to use newer versions of actions (actions/checkout@v5) and set explicit permissions for both linting and testing workflows. [1] [2] [3]
• Upgraded github/super-linter/slim from version v5 to v7 and added configuration to disable certain validations for markdown, natural language, and YAML prettier in .github/workflows/linter.yml.
• Added a new markdown lint configuration file .github/linters/.markdown-lint.yml to customize linting rules for markdown files.