Add non-requrired fields as inputs

[MNThomson]

Description

Currently, the provided example does not work. This is because in the action.yml file, the additional options aren't listed. Running the action with additional args results in an error:

- uses:seferov/pr-lint-action@master
  with:
    title-regex: '^\[\w*\](\ )'
    title-regex-flags: 'g'
    error-message: 'Add [] to beginning of PR title'

Unexpected input(s) 'title-regex-flags', 'error-message', valid inputs are ['entryPoint', 'args', 'title-regex']

Closes #231

Example

Take a look at this example PR (running CI from my fork) to show the output (running CI on this PR should fail since the CI is running against master).

Additional request to create a new release after the merge so that I can pin my actions as opposed to pinning to master (which is usually not a good idea)