mark nullable types explicitly

PHP 8.4 will throw a warning where type hints without a ?prefix are used
and nullable parameters can be passed.

I'm not sure if I found all occurances, but we still r

mark nullable types explicitly

PHP 8.4 will throw a warning where type hints without a ?prefix are used
and nullable parameters can be passed.

I'm not sure if I found all occurances, but we still rarely use type
hints, so it might not be many indeed.

show more ...

Apply rector fixes to inc/Subscriptions

♻️ Split up ChangesSubscriptionSender into multiple classes

This should better adhere to SRP and simplify things.

Automatic code style fixes for subscription classes

✅ Fix Subscriptions tests

This splits up and slightly refactors the tests for the refactored subscriptions classes

♻️ Extract subscription classes for PSR 2

This allows us to rename the snake_case methods and to group them in a
more sensible manner.