Fix deadlock when "packet ready" buffer is full

[kralverde]

Description

When the send packet function is invoked on the client, the lock on the encrypter was unnecessarily held for the remainder of the function. When a notification was sent to the server_packets_channel, the encrypter lock was still held, preventing the serialized packet from being taken and blocking the next call to the send packet function

Testing

You can verify this worked by teleporting to the world border.
Before: Deadlock
Now: Normally chunk loading

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[Snowiiii]

Nice. Thank you @kralverde 🚀