Auth listener unsubscribing during notification makes sign_out raise RuntimeError

[hsusul]

Describe the bug

An auth-state callback that unsubscribes itself causes sign_out() to raise RuntimeError: dictionary changed size during iteration. Other registered listeners then miss the sign-out event. This affects both SyncGoTrueClient and AsyncGoTrueClient, for example when a one-shot listener unregisters after handling its first event.

Reproduction

No running Supabase instance or credentials are needed:

from supabase_auth import SyncGoTrueClient

client = SyncGoTrueClient(
    url="http://localhost:9998",
    auto_refresh_token=False,
    persist_session=False,
)
received = []

def once(event, session):
    subscription.unsubscribe()

subscription = client.on_auth_state_change(once)
client.on_auth_state_change(lambda event, session: received.append(event))
client.sign_out()
assert received == ["SIGNED_OUT"]

Expected: sign-out completes, the second listener receives SIGNED_OUT, and the unsubscribed listener does not receive subsequent events.

Actual: _notify_all_subscribers() iterates a live dictionary view; subscription.unsubscribe() removes an entry during that iteration, causing RuntimeError before the second listener is called.

Environment

• Library: supabase_auth 2.31.0
• Reproduced on upstream main bb7ecc5fb86f5f8729c40a3885c6154d9b9f6262
• Python: 3.13.12