fix: pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-COMGOOGLEGUAVA-1015415
- https://snyk.io/vuln/SNYK-JAVA-COMGOOGLEGUAVA-32236
- https://snyk.io/vuln/SNYK-JAVA-IONETTY-30100
- https://snyk.io/vuln/SNYK-JAVA-IONETTY-30430

pom.xml

@@ -82,7 +82,7 @@
             <roles>
                 <role>Committer</role>
             </roles>
-            <timezone />
+            <timezone/>
         </developer>
         <developer>
             <id>afeng</id>
@@ -109,7 +109,7 @@
             <roles>
                 <role>Committer</role>
             </roles>
-            <timezone />
+            <timezone/>
         </developer>
         <developer>
             <id>jjackson</id>
@@ -193,7 +193,7 @@
         <clojure.tools.cli.version>0.2.4</clojure.tools.cli.version>
         <disruptor.version>2.10.4</disruptor.version>
         <jgrapht.version>0.9.0</jgrapht.version>
-        <guava.version>16.0.1</guava.version>
+        <guava.version>30.0-android</guava.version>
         <netty.version>3.9.0.Final</netty.version>
         <log4j-over-slf4j.version>1.6.6</log4j-over-slf4j.version>
         <log4j.version>2.1</log4j.version>
@@ -202,7 +202,7 @@
         <clojure-complete.version>0.2.3</clojure-complete.version>
         <mockito.version>1.9.5</mockito.version>
         <conjure.version>2.1.3</conjure.version>
-        <zookeeper.version>3.4.6</zookeeper.version>
+        <zookeeper.version>3.4.9</zookeeper.version>
         <clojure-data-codec.version>0.1.0</clojure-data-codec.version>
         <clojure-contrib.version>1.2.0</clojure-contrib.version>
         <hive.version>0.14.0</hive.version>