Describe the bug
When an xml opening tag contains an attribute and after that there is some whitespace, then the rainbow colouring does not work
To Reproduce
<a foo="" >
<b>
</b>
</a>
or
<a foo=""
>
<b>
</b>
</a>
For the first case replaying \>/ with \s*\>/ in the regex for start= works, but for the second there is probably some way that it needs to match over multiple lines