datasource reloaded with rxSwift

[rnjstjddn96]

New Issue Checklist

• [x] Updated Tabman to the latest version
• [x] I took a look at the Troubleshooting Guide
• [x] I searched for existing GitHub issues

Issue Description

Hi, I'm currently using Tabman with rxSwift, and found viewControllers in tabman being refreshed everytime I navigate with buttons, or swping all the way to the end, and come back to the first one.

I found that

viewController(for pageboyViewController: PageboyViewController, at index: PageboyViewController.PageIndex) -> UIViewController?

method in 'PageboyViewControllerDataSource' called multiple time while moving through pages.

please leave a comment if anyone having similar issue. thank you