Update to Jackson 2.9.8

Problem/Solution

Update Jackson dependencies to version `2.9.8`.

JIRA Issues: CSL-7986

Differential Revision: https://phabricator.twitter.biz/D304193

build.sbt

@@ -3,11 +3,11 @@ import scoverage.ScoverageKeys
 // All Twitter library releases are date versioned as YY.MM.patch
 val releaseVersion = "19.5.0-SNAPSHOT"
 
-val jacksonVersion = "2.9.6"
+val jacksonVersion = "2.9.8"
 val jacksonLibs = Seq(
   "com.fasterxml.jackson.core" % "jackson-core" % jacksonVersion,
   "com.fasterxml.jackson.core" % "jackson-databind" % jacksonVersion,
-  "com.fasterxml.jackson.module" %% "jackson-module-scala" % jacksonVersion
+  "com.fasterxml.jackson.module" %% "jackson-module-scala" % jacksonVersion exclude("com.google.guava", "guava")
 )
 val opencensusVersion = "0.19.1"
 val slf4jVersion = "1.7.21"