Don't use deprecated code

Author: garydgregory

src/test/java/org/apache/commons/csv/CSVPrinterTest.java

@@ -1516,7 +1516,7 @@ public void testPrintRecordsWithCSVRecord() throws IOException {
     public void testPrintRecordsWithEmptyVector() throws IOException {
         final PrintStream out = System.out;
         try {
-            System.setOut(new PrintStream(NullOutputStream.NULL_OUTPUT_STREAM));
+            System.setOut(new PrintStream(NullOutputStream.INSTANCE));
             try (CSVPrinter csvPrinter = CSVFormat.POSTGRESQL_TEXT.printer()) {
                 final Vector<CSVFormatTest.EmptyEnum> vector = new Vector<>();
                 final int expectedCapacity = 23;