update pdfbox to 2.0.28

Author: THausherr

pom.xml

@@ -262,7 +262,7 @@
     <dependency>
         <groupId>org.apache.pdfbox</groupId>
         <artifactId>pdfbox</artifactId>
-        <version>2.0.26</version>
+        <version>2.0.28</version>
     </dependency>
 
     <dependency>