Upgrade AutoCommon 1.2 -> 1.2.1 (#49)

See:
- https://github.com/google/auto/releases/tag/auto-common-1.2.1
- google/auto@auto-common-1.2...auto-common-1.2.1

pom.xml

@@ -197,7 +197,7 @@
             <dependency>
                 <groupId>com.google.auto</groupId>
                 <artifactId>auto-common</artifactId>
-                <version>1.2</version>
+                <version>1.2.1</version>
             </dependency>
             <dependency>
                 <groupId>com.google.auto.service</groupId>