Update ZK version to 3.5.7 (#329)

diff --git a/conf/checksums b/conf/checksums
index 68c6eb4..64ed559 100644
--- a/conf/checksums
+++ b/conf/checksums
@@ -29,6 +29,7 @@
 spark:2.3.3:a5c4a54db5163df25110534f36e13d6ae65758d45d1bc8bfcd7e27304e716a23
 spark:2.3.2:3387107155d62f04ccf6bcaf2e00a69a0de5ae5df875348d93147743c206f0a8
 spark:2.2.2:023b2fea378b3dd0fee2d5d1de6bfaf2d8349aefe7be97a9cbcf03bbacc428d7
+zookeeper:3.5.7:b9baa1ecb3d4dc0ef648ce7c74da4c5267ee89534c7614b8f27d3b0bc52004dcfbb8cecec810ffb7c8c45053daf8a5e849ce60ba241280fa1e2ab1d3b4990494
 zookeeper:3.5.6:db24700e453f2ad4b6b789d553fe828ccceef3977a7e6b36389580ec92397a7e
 zookeeper:3.4.14:b14f7a0fece8bd34c7fffa46039e563ac5367607c612517aa7bd37306afbd1cd
 zookeeper:3.4.13:7ced798e41d2027784b8fd55c908605ad5bd94a742d5dab2506be8f94770594d
diff --git a/conf/muchos.props.example b/conf/muchos.props.example
index 9fb5854..927d22d 100644
--- a/conf/muchos.props.example
+++ b/conf/muchos.props.example
@@ -37,7 +37,7 @@
 accumulo_password = secret
 # Software versions (make sure you have a corresponding entry for the checksum in conf/checksums)
 hadoop_version = 3.2.1
-zookeeper_version = 3.5.6
+zookeeper_version = 3.5.7
 spark_version = 2.4.5
 fluo_version = 1.2.0
 fluo_yarn_version = 1.0.0