Bug on repeating table header when using page-break-after: avoid; inside table

Hello,

I found an issue when using page-break-after: avoid; in a table:

I have a use case where I need to keep together two elements.
I created two reproducers to illustrate better the issue:

Source:
[category_children_on_different_page.txt](https://github.com/danfickle/openhtmltopdf/files/4320381/category_children_on_different_page.txt)

Produces:
[category_children_on_different_page.pdf](https://github.com/danfickle/openhtmltopdf/files/4320384/category_children_on_different_page.pdf)


The problem here is the text "CATEGORY" is on page1, but his children started on page2. I would like to keep then together. So, I put this code: (just added page-break-after: avoid; on tbody)
```


CATEGORY

```

Indeed, CATEGORY now is together with its children, BUT the repeating header is gone:

Source:
[category_together_with_children_but_bug_on_repeating_header.txt](https://github.com/danfickle/openhtmltopdf/files/4320401/category_together_with_children_but_bug_on_repeating_header.txt)

Produces:
[category_together_with_children_but_bug_on_repeating_header.pdf](https://github.com/danfickle/openhtmltopdf/files/4320403/category_together_with_children_but_bug_on_repeating_header.pdf)


All the contents are dynamic, so I don't know in advance how big will be itens or subitens. So far the only way I could achieve the desired output was using "page-break-after: avoid;".
I tried using widows / orphans, but I guess it does not work on tables.

Thanks for this great library. Hope you can continue this great work.

Best wishes,
lagar84.