Upgrade AutoValue 1.8.2 -> 1.9 (#83)

See:
- https://github.com/google/auto/releases/tag/auto-value-1.9
- google/auto@auto-value-1.8.2...auto-value-1.9

pom.xml

@@ -126,7 +126,7 @@
         one place. We use these to keep dependencies in sync. Version numbers
         that need to be referenced only once should *not* be listed here. -->
         <version.auto-service>1.0.1</version.auto-service>
-        <version.auto-value>1.8.2</version.auto-value>
+        <version.auto-value>1.9</version.auto-value>
         <version.error-prone>${version.error-prone-orig}</version.error-prone>
         <version.error-prone-fork>v${version.error-prone-orig}-picnic-1</version.error-prone-fork>
         <version.error-prone-orig>2.10.0</version.error-prone-orig>