Fix MarkupTest's missing array code convention

[GREENOVER]

Summary

Found the missing code convention of the array in the MarkupTest code.
So, add it to this.

Checklist

• Added tests
• Ran the ./bin/test script and it succeeded

[Monsteel]

Cool😃
I agree this PR's suggestion!🙌

[franklinsch]

I see this file is generally using trailing commas for the last elements of array—thanks for spotting this and opening a PR! If we do want to be consistent with the trailing commas here, it looks like some other places are missing it, so we should update those as well I'd say.

[GREENOVER]

@franklinsch
Thank you👍🏻
I think so, too.
Currently, other files have not yet found the same part as the this PR.
If it is found after an overall inspection, I will additionally commit it :)

[GREENOVER]

@franklinsch
I reviewed all the files to find and add two parts that did not fit the array convention.
I hope it will be reflected for the perfection of the code.

[franklinsch]

@swift-ci test

[franklinsch]

@swift-ci please test Linux

[franklinsch]

@swift-ci please test Linux

[franklinsch]

@swift-ci please test macOS