Fix: increase max block gas limit

Increase the block gas limit accordingly as we update the gas configuration.

gno.land/cmd/gnoland/start.go

@@ -374,7 +374,7 @@ func generateGenesisFile(genesisFile string, pk crypto.PubKey, c *startCfg) erro
 			// TODO: update limits.
 			MaxTxBytes:   1_000_000,   // 1MB,
 			MaxDataBytes: 2_000_000,   // 2MB,
-			MaxGas:       100_000_000, // 100M gas
+			MaxGas:       3_000_000_000, // 3B gas
 			TimeIotaMS:   100,         // 100ms
 		},
 	}