secure transport: allow more sessions

Sessions were limited to 256 for some reason.
For large scale operation it makes sense to allow more
open sessions (symmetric key sessions).

Signed-off-by: Csaba Kiraly <csaba.kiraly@gmail.com>

libp2pdht/private/eth/p2p/discoveryv5/transport.nim

@@ -217,5 +217,5 @@ proc newTransport*[T](
     codec: Codec(
       localNode: localNode,
       privKey: privKey,
-      sessions: Sessions.init(256)),
+      sessions: Sessions.init(100000)),
     rng: rng)