build: fix find-inactive-collaborators workflow token

Use a token that will result in GitHub CI running on the pull requests
that this workflow opens.

PR-URL: https://github.com/nodejs/node/pull/39909


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>