Correct serialization error type.

Author: kinyoklion

lib/sdk/server/src/test/java/com/launchdarkly/sdk/server/PollingInitializerImplTest.java

@@ -5,7 +5,7 @@
 import com.launchdarkly.sdk.server.datasources.FDv2SourceResult;
 import com.launchdarkly.sdk.server.datasources.SelectorSource;
 import com.launchdarkly.sdk.server.interfaces.DataSourceStatusProvider;
-import com.launchdarkly.sdk.server.subsystems.SerializationException;
+import com.launchdarkly.sdk.json.SerializationException;
 
 import org.junit.Test;