fix: update bittensor-rs to 99b6325 (wall-clock reveal_round + correct DRAND genesis)

The reveal_round calculation was using chain's LastStoredRound as base,
diverging from the reference bittensor-drand SDK which uses wall-clock time.
This caused weight divergence between Rust and Python validators.

Also fixes DRAND_QUICKNET_GENESIS (was wrong value) and adds 3-block
security offset matching the reference implementation.

Author: echobt

Cargo.lock

@@ -37,7 +37,7 @@ license = "Apache-2.0"
 [workspace.dependencies]
 # Bittensor (with CRv4 timelock encryption support and new Subtensor API)
 # Updated to d2ca7c2: fix epoch calculation to match subtensor formula
-bittensor-rs = { git = "https://github.com/CortexLM/bittensor-rs", rev = "c33a811" }
+bittensor-rs = { git = "https://github.com/CortexLM/bittensor-rs", rev = "99b6325" }
 
 # Async runtime
 tokio = { version = "1.40", features = ["full", "sync", "macros", "rt-multi-thread"] }