only allow ruby regex whitespace chars in raw tag delimiters

[ggmichaelgo]

What are you trying to solve?

Liquid-C does not parse raw tag's delimiter like Liquid. Liquid does not allow non-word characters to be part of the delimiter, but Liquid-C does.

For an example, Liquid-C should raise a syntax error for this Liquid template:

{% raw %}

{% 🔥endraw %}

Since 🔥endraw is an invalid delimiter for the raw tag, Liquid-C should raise a syntax error like Liquid:

Liquid syntax error: 'raw' tag was never closed (Liquid::SyntaxError)