build Atrium against jdk13 and jdk14

[robstoll]

Platform (jvm, js, android):
Extension (none, kotlin 1.3, jdk8): none

Code related feature

We want to check if Atrium builds against jdk13 and jdk14
We already tried and saw that some tests fail as there is an issue with mockk.

Following the things you need to do:

• add jdk13 and jdk14 to the github action windows build as in this commit (you can copy and paste) https://github.com/robstoll/atrium/pull/449/files
• fix the issue with mockk

[robstoll]

Most likely mockk does not support jdk13 and jdk14 yet. I opened a bug: mockk/mockk#428

[oleksiyp]

I did a few commits today to MockK develop branch and test on JDK 13/14. Seems everything works. The current issue is with dokka. Not sure how am going to release it

[robstoll]

Thanks for the heads up, is there already an issue for dokka? I couldn't find any in a hurry, I would upvote it.

[oleksiyp]

This is quite a long-running issue. Kotlin/dokka#294