update samples/spark/pet-store/pom.xml fix ref

Fix version reference to this library (latest release, 0.4), updated ref lets maven compile

Author: yyolk

samples/spark/pet-store/pom.xml

@@ -34,7 +34,7 @@
         <dependency>
             <groupId>com.amazonaws.serverless</groupId>
             <artifactId>aws-serverless-java-container-spark</artifactId>
-            <version>0.1</version>
+            <version>0.4</version>
         </dependency>
 
         <dependency>
@@ -111,4 +111,4 @@
             </plugin>
         </plugins>
     </build>
-</project>
+</project>