added support fractional seconds for time types. Actually for MySQL >= 5.6.4

[kos-v]

Q	A
Is bugfix?	yes
New feature?	yes
Breaks BC?	no
Tests pass?	yes
Fixed issues	#14367

[yii-bot]

Thank you for putting effort in the improvement of the Yii framework.
We have reviewed your pull request.

In order for the framework and your solution to remain stable in the future, we have a unit test requirement in place. Therefore we can only accept your pull request if it is covered by unit tests.

Could you add these please?

Thanks!

P.S. If you have any questions about the creation of unit tests? Don't hesitate to ask for support. More information about unit tests

This is an automated comment, triggered by adding the label pr:request for unit tests.

[samdark]

Merged. Thank you!