v6.4.0

Changelog (v6.4.0-RC2...v6.4.0)

• bug #52786 [Serializer] Revert allowed attributes fix (@mtarld)
• bug #52765 [Translation] Remove @internal from abstract testcases (@OskarStark)
• bug #52780 [DependencyInjection] don't check parameter values if they are not set (@xabbuh)
• bug #52762 [VarExporter] Work around php/php-src#12695 for lazy objects, fixing nullsafe-related behavior (@nicolas-grekas)
• bug #52759 [VarExporter] Fix serializing objects that implement __sleep() and that are made lazy (@nicolas-grekas)
• bug #52767 [Serializer] Fix normalization relying on allowed attributes only (@mtarld)
• bug #52727 [String] Fix Inflector for 'icon' (@podhy)

[PR] #52790