[Kaizen] Sagano target block time 15s (#989)

Author: dzajkowski

src/main/resources/conf/chains/testnet-internal-nomad-chain.conf

@@ -5,7 +5,7 @@
 
     # Possibility to set Proof of Work target time for testing purposes.
     # null means that the standard difficulty calculation rules are used
-    pow-target-time = 10 seconds
+    pow-target-time = 15 seconds
 
     # Frontier block number
     frontier-block-number = "0"