allow upper case letters in domain part of emails and fix local part …

See merge request !23

switch to gitlab-ci and move project

See merge request !24

This change also proves the domain part in more detail. Such as consecutive dashes or dots are not allowed.

use github actions for CI and add compatibility to php 8

make validator and filter invokable

execute `Field::filter()` in `Field::validate()`

This ensures that the value given is filtered before it get's validated.
Beside that `Field::filter()` gets now executed twice what is acceptable
because filters caches (when possible) the filtered value.

test only for integer when string is numeric

`(double)'foo'` always returns 0 what is an integer too.

/solves #17

Unfortunately case is a keyword and we can not use it as class name.

We need this for example when we don't want a specific card type:
`['creditCard', '!credictCard:amex:dinersclub']`