fix: use core.getBooleanInput() to retrieve boolean input values (#223)

This PR switches from evaluating values passed to `skip-token-revoke` as
true if they are truthy in JavaScript, to using `getBooleanInput`. This
change ensures that only proper YAML boolean values are recognized,
preventing unintended evaluations to true.
- The definition of `getBooleanInput` is here: definition of
`core#getBooealnInput` is here:
930c890727/packages/core/src/core.ts (L188-L208)

The documentation states, `"If truthy, the token will not be revoked
when the current job is complete"`, so this change could be considered a
breaking change. This means that if there are users who rely on `truthy`
and expect values like whitespace or `"false"` to be evaluated as true
(though this is likely rare), it would be a breaking change.
- `Boolean(" ")` and `Boolean("false")` are both evaluated as true.

Alternatively, it can simply be considered a fix. How to handle this is
up to the maintainer.

Resolves https://github.com/actions/create-github-app-token/issues/216

lib/post.js

@@ -5,7 +5,7 @@
  * @param {import("@octokit/request").request} request
  */
 export async function post(core, request) {
-  const skipTokenRevoke = Boolean(core.getInput("skip-token-revoke"));
+  const skipTokenRevoke = core.getBooleanInput("skip-token-revoke");
 
   if (skipTokenRevoke) {
     core.info("Token revocation was skipped");