feat: use dash notation for inputs (deprecates underscore notation)

[smockle]

Fixes #57

This PR implements the 3-step plan proposed by @gr2m in https://github.com/actions/create-github-app-token/issues/57#issuecomment-1751272252:

1. Support both input types
2. Log a deprecation warning for the old notation
3. Add a test for deprecations

Although this PR supports both input formats simultaneously, I opted not to document the old format in the updated README. That’s a decision I’m happy to revisit, if y’all would prefer to have documentation for both the old and new formats.

[parkerbxyz]

This is great. Thanks, @smockle! ✨

Although this PR supports both input formats simultaneously, I opted not to document the old format in the updated README.

I agree with this approach. 🙂

[gr2m]

interesting side effect of this PR: the release build failed because it's using the stable version: https://github.com/actions/create-github-app-token/actions/runs/6436042980

We should use the local version instead, like in tests

I'm on it

[create-app-token-action-releaser[bot]]

:tada: This PR is included in version 1.5.0 :tada:

The release is available on GitHub release

Your semantic-release bot :package::rocket: