Add a dep on the Java 8 Truth extension

MOE_MIGRATED_REVID=210113065
diff --git a/pom.xml b/pom.xml
index 7e15de0..209df22 100644
--- a/pom.xml
+++ b/pom.xml
@@ -22,7 +22,7 @@
     <dependency>
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
-      <version>23.6-jre</version>
+      <version>25.1-jre</version>
     </dependency>
     <dependency>
       <groupId>com.google.errorprone</groupId>
@@ -67,7 +67,13 @@
     <dependency>
       <groupId>com.google.truth</groupId>
       <artifactId>truth</artifactId>
-      <version>0.36</version>
+      <version>0.42</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>com.google.truth.extensions</groupId>
+      <artifactId>truth-java8-extension</artifactId>
+      <version>0.42</version>
       <scope>test</scope>
     </dependency>
     <dependency>