store header char check too strict?

Not sure what is correct here but a test in undici started to fail in node 19 with:

`Invalid character in header content ["content-disposition"]`

With:

```js
    res.writeHead(200, {
      'content-length': 2,
      'content-disposition': "attachment; filename='år.pdf'"
    })
```

I don't think `å` should cause problems?