Add none option for inverse matching the changes to a label

[ashleyfrieze]

Description:
We have a requirement to add an advisory label to PRs where there's missing documentation change or missing unit tests.

This seems to fit into the labeler model via a new top level key none.

Please consider this PR for inclusion in this useful action.

Related issue:
Add link to the related issue.

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.

[Copilot]

Pull Request Overview

This PR adds a new none option to the labeler action that enables inverse matching for labels. This allows users to apply labels when certain conditions are NOT met, such as when documentation or test files are missing from a PR.

• Adds none matching option to complement existing any and all options
• Updates type definitions and configuration parsing to support the new option
• Adds comprehensive test coverage for the new functionality

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/labeler.ts	Implements the core logic for none matching using inverse of checkAny
src/api/get-label-configs.ts	Adds none to type definitions and configuration parsing
tests/labeler.test.ts	Adds test cases for both positive and negative none matching scenarios
tests/fixtures/all_options.yml	Updates test fixture to include none configuration examples
README.md	Documents the new none option with examples and usage guidance

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