Update BOM to 3.2.0 (#63)

@kolea2 deliberately staying off 3.3.0 until a bug is fixed here

README.md

@@ -19,7 +19,7 @@ If you are using Maven with Bom, Add this to your pom.xml file.
   <dependency>
     <groupId>com.google.cloud</groupId>
     <artifactId>libraries-bom</artifactId>
-    <version>3.0.0</version>
+    <version>3.2.0</version>
     <type>pom</type>
     <scope>import</scope>
    </dependency>