chore(deps): bump nexus to e1f0b68 and pylon to 2.1.0 (#3)

Pull in the Nexus host-root-logger fix (e1f0b68) so the validator's structlog
JSON logging is no longer clobbered by Litestar. The new Nexus requires
bittensor-pylon-client 2.1.0, so bump the localnet pylon server to match.
Verified end-to-end on localnet: JSON logs, weight setting, and keyfile
signing all work against pylon 2.1.0.

Author: kacper-wolkiewicz-reef

localnet/compose.yml

@@ -11,7 +11,7 @@ services:
       retries: 10
 
   pylon:
-    image: backenddevelopersltd/bittensor-pylon:2.0.0
+    image: backenddevelopersltd/bittensor-pylon:2.1.0
     ports:
       - "8000:8000"
     environment: