Why is Renovate Bot not running anymore?

I added Renovate Bot to a couple of private GitHub repos a few months ago and it's been working fine until this month. One of the repos uses Gradle and the other uses NPM (package.json).

The dependencies should be updated on the 6th day of every month. In the case of the Gradle repo they were updated this month, but no PRs were created for the NPM repo. I have verified that there are pending updates for the dependencies in the NPM repo.

My guess is that the GitHub access token that is used to create the PRs has expired, but I've no idea where to find this token, or how to update it.

The renovate.json config file is shown below:

{
  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
  "extends": [
    "config:base"
  ],
  "schedule": [
    "before 3am on the 6th day of the month"
  ],
  "ignoreDeps": ["postgres", "sass"],
  "packageRules": [
    {
      "matchPackagePatterns": [
        "*"
      ],
      "matchUpdateTypes": [
        "minor",
        "patch"
      ],
      "groupName": "all non-major dependencies",
      "groupSlug": "all-minor-patch"
    }
  ]
}