feat(symfony): Add support for Symfony 8

[damienalexandre]

Goal

Symfony 8 has been released, this PR allow installing the bundle on it.

Changeset

• Added Symfony 8
• Fixed deprecation and errors (Symfony deprecation message about internal class usage #186 as well)

Testing

make is green. I suspect old versions are not going to like the typehint.

[derrabus]

Adding return types won't work as long as this bundle still supports PHP 5.

[damienalexandre]

Yes I had to do it because it's mandatory since PHP 8.2 : https://3v4l.org/Pi1eW#vnull and added in the Symfony Interface since Symfony 8.0 (symfony/symfony#60697).

Maybe we can wrap this class in a condition (like this), so we can have two implementation?

WDYT?

EDIT: just tested https://3v4l.org/dZ4OT#v5.6.5 and the parser is still screaming:

Parse error: syntax error, unexpected ':', expecting ';' or '{' in /in/dZ4OT on line 19

So it would needs to be handled by the autoloader somehow.

[agrzegorzewski]

Hi @damienalexandre,
Thanks for bringing this issue to our attention.
We will include your changes as a part of our next release which will add support for Symfony 8. As noted by @derrabus, due to the syntax incompatibility this will result in us dropping support for PHP 5 and releasing a new major version of the notifier.
#188