Allow colons in class names

[hakoerber]

When using class names that contain colons (:), I get the following error:

thread 'tokio-runtime-worker' panicked at 'called `Result::unwrap()` on an `Err` value: "class name can only contain alphanumerics, dash, dot and underscore"'

This is coming from this check.

Now, I did not find anything in the HTML spec that actually forbids colons (actually, it allows everything but whitespace). At least colons are quite frequently used for pseudo classes in tailwind (e.g. hover:bg-purple-100).

So I propose to allow colons for classes (and also ids for good measure, it uses the same check). If you agree, I'll open a pull request, should be easy to change.

UPDATE: I changed it in my fork, works like a charm. I'll open a PR if you want.