time/ruby-timers: update to 4.3.3

4.3.3 (2021-02-13)

No release note nor changelog.  Here is quote from commit log.

* Fix development workflow.
* Remove comment from gemspec.
* Add priority queue class
* Add #size method and change to actual minheap
* Add some tests for priority heap
* Rename first and insert to peek and push for naming consistency
* Switch to a PriorityHeap instead of array for storing Handles
* Refactor Handle class to use Comparable mixin
* Add extra performance test for timer queue insertion speed
* Reduce required accuracy for tests, because macOS on GitHub Actions i… …
* Updated code formatting & specs.

(taca)