Update jsonNodeFactory following deprecation warnings

Author: manas-ctds

connector/src/main/java/com/datastax/oss/pulsar/source/converters/NativeJsonConverter.java

@@ -58,7 +58,7 @@
 public class NativeJsonConverter extends AbstractNativeConverter<byte[]> {
     private static final ObjectMapper mapper = new ObjectMapper();
 
-    private static final JsonNodeFactory jsonNodeFactory = JsonNodeFactory.withExactBigDecimals(true);
+    private static final JsonNodeFactory jsonNodeFactory = JsonNodeFactory.builder().exactBigDecimals(true).build();
 
     public NativeJsonConverter(KeyspaceMetadata ksm, TableMetadata tm, List<ColumnMetadata> columns) {
         super(ksm, tm, columns);