Xitrum 3.28.5

[Ngoc Dao]

Xitrum 3.28.5 has been released.

Changes:
* #651 xitrum.Server.stop should wait until Xitrum is stopped; add stopAtShutdown
* #654 Update dependency libraries

See:
https://github.com/xitrum-framework/xitrum/blob/master/CHANGELOG.rst

There's no Xitrum API change, other than the stopAtShutdown addition above.

To update your project from Xitrum 3.28.4 to 3.28.5, simply update its version number.
Example:
https://github.com/xitrum-framework/xitrum-new/commit/7abdde512530bcc2745f3a936dc87fe5982df761