Update multiplayer pong to godot 4 beta 5

[scriptsengineer]

No description provided.

[Faless]

See my comments on the preferred RPC syntax, other RPCs not touched by the code should also be updated to that format.

[scriptsengineer]

Update all rpcs with new syntax: 3cab28e

[Faless]

Looks good now 👍 , thanks for updating the demo 🏆 .
Note that, before we can merge, you will have to squash you commits together.
See here for more info: https://docs.godotengine.org/en/latest/community/contributing/pr_workflow.html#the-interactive-rebase

[scriptsengineer]

Successfully squashed commits

[Faless]

Thanks!