Allow finding issues on another repo & drop env. variables

Breaking changes:

• all outputs are following a common naming conventions:
  kebab case
  • issue_number is now issue-number
  • has_found is now has-found
  • is_closed is now is-closed
• environment variable were moved to action inputs
  • GITHUB_TOKEN is now token and defaults to github.token

Features:

• New optional input added: repository. Now you can fetch issues on other
  repository instead of on the one that the action runs.

---

PR: #6

Dependencies upgrade & minor general improvements

• upgrade all dependencies to their latest version
• patch node-fetch (dependency of @octokit/rest package) to fix security issues
• minor refactorings to the source
• minor improvements to the documentation

It's small now!

(just drop the useless node_modules dir)

Expose `is_closed` issue value

v1.2.0

feat: build for release

Support filtering by closed issues

v1.1.0

feat: build for release

First production-ready release

v1.0.4

feat: build for release

First version

v1.0.1

feat: build for release