Add com.google.truth as test dependencies

This goes hand-in-hand with other dependencies like junit, but seems to
only have been used from util/pom.xml.

java/core/pom.xml

@@ -37,6 +37,11 @@
       <artifactId>guava</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>com.google.truth</groupId>
+      <artifactId>truth</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>

java/lite/pom.xml

@@ -37,6 +37,11 @@
       <artifactId>guava</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>com.google.truth</groupId>
+      <artifactId>truth</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>