chore(main): release 2.6.4

[github-actions[bot]]

:robot: I have created a release beep boop

2.6.4 (2023-06-14)

Code Refactoring

• fix assertionerror when registering copied generic types on schema directives (#238) (250da52)

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[github-actions[bot]]

:robot: Release is at https://github.com/blb-ventures/strawberry-django-plus/releases/tag/v2.6.4 :sunflower: