fix(Portal): fix event handling for mouseEnter/mouseLeave

[tourman]

Fixing https://github.com/Semantic-Org/Semantic-UI-React/issues/4442 and other other similar typo.

[welcome[bot]]

💖 Thanks for opening this pull request! 💖

Here is a list of things that will help get it across the finish line:

• Run yarn lint locally to catch formatting errors. This will fix some errors automatically, commit and push any changes.
• Run yarn test locally to catch errors. This ensures all components still behave as they should.
• Run yarn start to run the doc site locally and try a few pages, ensuring everything is in good working order.
• Include tests when adding/changing behavior.

We get a lot of pull requests on this repo, so please be patient and we will get back to you as soon as we can.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (ba4b720) 99.51% compared to head (eb03d99) 99.51%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #4445 +/- ## ======================================= Coverage 99.51% 99.51% ======================================= Files 186 186 Lines 3511 3511 ======================================= Hits 3494 3494 Misses 17 17 ```

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[welcome[bot]]

Congrats on merging your first pull request! 🎉🎉🎉

[dimitur2204]

@layershifter Is there a date/schedule for the release for this one?

[layershifter]

Released in 3.0.0-beta.2 🎉