Updated log4j to version 2.16.0 to further mitigate CVE-2021-44228 (#…

…7605)

build.gradle

@@ -71,7 +71,7 @@ final disqVersion = System.getProperty('disq.version','0.3.6')
 final genomicsdbVersion = System.getProperty('genomicsdb.version','1.4.2')
 final bigQueryVersion = System.getProperty('bigQuery.version', '1.117.1')
 final guavaVersion = System.getProperty('guava.version', '27.1-jre')
-final log4j2Version = System.getProperty('log4j2Version', '2.15.0')
+final log4j2Version = System.getProperty('log4j2Version', '2.16.0')
 final testNGVersion = '7.0.0'
 
 // Using the shaded version to avoid conflicts between its protobuf dependency