Migration to Central Portal needed

Publishing to Maven Central will require that you migrate to using the Central Portal soon.

See (internally) http://go/central-portal-migration-com-squareup for context.

Here is an example migration: https://github.com/square/okio/pull/1621. Do not perform the migration of this repo until that example PR has been merged indicating it is safe to do so. If you prefer, you can create your own migration PR on this repo and comment on this issue with a link. I will then merge your PR as part of the migration.

You should also check that you are using the new GPG signing key. Configuration in your GitHub workflow YAML should look like this:
```yaml
ORG_GRADLE_PROJECT_signingInMemoryKey: ${{ secrets.GPG_SECRET_KEY }}
ORG_GRADLE_PROJECT_signingInMemoryKeyPassword: ${{ secrets.GPG_SECRET_PASSPHRASE }}
```

Your project has not been automatically updated because:
- Dependencies too old (requires publish plugin 0.28.0 or newer, 0.31.0 or newer for snapshots)