fix(owners): adjust list files function using correct options for PR #
fix(owners): adjust list files function using correct options for PR #

To fix the nodejs/node PR owners ping functionality, these changes
adjusts the internal helper function used to list affected files in a PR
to ensure it provides the correct pull request number.

Fixes bug originally introduced in https://github.com/nodejs/github-bot/commit/7b4ac859952163479b2afe159cf0ff29416b37bb
when `.number -> .pull_number` changes was introduced. It broke the
said helper function, which at that time expected an object containing
`.pull_number` provided as argument, but ended up getting the GitHub
webhook event `options` provided, where that PR number is represented in
`.prId`.

nodejs/github-bot