Update to node16 and cleanup node_modules

[nirinchev]

This updates actions to node16 as node12 is deprecated. Additionally, I noticed we're committing node_modules which is a bad practice. I've deleted the folder and added a .gitignore.

[bwachter]

https://docs.github.com/en/actions/creating-actions/creating-a-javascript-action#commit-tag-and-push-your-action-to-github

"GitHub downloads each action run in a workflow during runtime and executes it as a complete package of code before you can use workflow commands like run to interact with the runner machine. This means you must include any package dependencies required to run the JavaScript code."

[nirinchev]

Yes, the recommended way to do it is via ncc, not by checking in node_modules. I've added a build script that compiles the dependencies into a single file.

[bwachter]

Looks good to me. Switching bool input handling over to getBooleanInput is tracked in #11 - my best guess still is that something weird was going on in input validation there.