Bugfix in ZF2ZInvoiceImporterTest: Make test work on case sensitive file systems

The generated file is named "testout-ZF2new.pdf" not "testout-ZF2New.pdf"
which will make the test fail on case sensitive file systems as can be
found on many unix like systems.

library/src/test/java/org/mustangproject/ZUGFeRD/ZF2ZInvoiceImporterTest.java

@@ -41,7 +41,7 @@ import junit.framework.TestSuite;
  * used for this import, testout-ZF2New.pdf
  */
 public class ZF2ZInvoiceImporterTest extends TestCase  {
-	final String TARGET_PDF = "./target/testout-ZF2New.pdf";
+	final String TARGET_PDF = "./target/testout-ZF2new.pdf";
 
 	public void testInvoiceImport() {