Update pool package in pub.dev

[ristiisa]

Update https://pub.dev/packages/pool package to point to correct repo location

[devoncarew]

Thanks for the issue! It looks like we'd need to remove the -wip from here: https://github.com/dart-lang/tools/blob/main/pkgs/pool/pubspec.yaml and the changelog, and re-publish. Happy to take a PR to do this.