zcash_protocol: Set the public testnet activation height for NU6

components/zcash_protocol/src/consensus.rs

@@ -383,7 +383,7 @@ impl Parameters for TestNetwork {
             NetworkUpgrade::Heartwood => Some(BlockHeight(903_800)),
             NetworkUpgrade::Canopy => Some(BlockHeight(1_028_500)),
             NetworkUpgrade::Nu5 => Some(BlockHeight(1_842_420)),
-            NetworkUpgrade::Nu6 => None,
+            NetworkUpgrade::Nu6 => Some(BlockHeight(2_976_000)),
             #[cfg(zcash_unstable = "zfuture")]
             NetworkUpgrade::ZFuture => None,
         }