Updates dependency google-api-services-datastore-protobuf.

----Release Notes----
Updating dependency google-api-services-datastore-protobuf from v1beta2-rev1-2.1.2 to v1beta2-rev1-3.0.2.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=103114238

Author: chamikaramj

sdk/pom.xml

@@ -450,7 +450,7 @@
     <dependency>
       <groupId>com.google.apis</groupId>
       <artifactId>google-api-services-datastore-protobuf</artifactId>
-      <version>v1beta2-rev1-2.1.2</version>
+      <version>v1beta2-rev1-3.0.2</version>
       <exclusions>
         <!-- Exclude an old version of guava that is being pulled
              in by a transitive dependency google-api-client 1.19.0 -->