Release 3.3.0 incoming

Hi everyone,

I worked on all the opened issues and PR that don't required overhauling the library. I released version 3.3.0b1 and will release version 3.3.0 final in the coming days or weeks.
Please give feedback here if you notice things that deserve changes before 3.3.0 final. We can still change the API. I will try to reach a few maintainers of projects depending on wtforms before cutting the release.

The full changelog is here. Most changes are non breaking but those points may require attention:

• the (re)introduction of the SelectChoice dataclass might break fields inheriting SelectField and expecting iter_choices to return a list of tuples, now this is a list of SelectChoice.
• SelectField no longer has has_groups and iter_groups
• URL no longer inherits Regexp, and use urllib internally to parse urls. It accepts only http and https by default, other schemes must be whitelisted with schemes=
• FloatField default widget is NumberInput and no longer TextInput

After this, and I won't promise exactly when, I will work on the remaining tickets for wtforms v4. This version will have breaking changes as I want to rework the form processing part so it is more consistent, the field binding part etc. It should bring interesting features too, such as type annotations #618, multiple fields #799, maybe async #839.

There will maybe be an intermediate 3.4 release containing compatibility helpers for v4 and deprecation warnings.

/cc @PanderMusubi @Daverball @ThiefMaster @davidism @TurnrDev

Start with the linked version 3.3.0b1 changelog, then review the listed API changes involving SelectChoice, SelectField, URL, and FloatField. Check the compatibility concerns raised in the issue and the surrounding comments; done means actionable feedback has been resolved before the final 3.3.0 release.