Allow skipping the changed files check

[KyeRussell]

I am attempting to add this action to an existing repository.

As the action only runs Packj on changed dependency files, I do not see a way to run an 'initial' scan on the repository's dependencies, without updating the dependency files themselves.

I can of course manually run Packj on my dependencies locally. Though I think that it'd be a good idea to allow bypassing this check, not only for my use case, but for others, too. For example:

• I may want to leave "have these files changed?" check up to the GitHub Actions workflow's on: directive, e.g.:

  on:
    push:
      paths:
        - "package.json"

• I may want to check dependencies based on other conditions:
  • Packj's output is not deterministic based on just the dependency set. Put another way: many of Packj's checks' outputs could change over time, with my dependencies remaining the same.
  • Organisational / regulatory requirements may necessitate regular checks.