fix PdfLoader after pdf2htmlEx bump

Author: andiwand

app/src/main/java/at/tomtasche/reader/background/PdfLoader.java

@@ -47,7 +47,9 @@ public void loadSync(Options options) {
             File cacheDirectory = AndroidFileCache.getCacheDirectory(cacheFile);
 
             pdf2htmlEX pdfConverter = new pdf2htmlEX(context).setInputPDF(cacheFile);
-            pdfConverter.setOutline(false).setBackgroundFormat("jpg").setDRM(false);
+            pdfConverter.setProcessOutline(false);
+            pdfConverter.setBackgroundImageFormat(pdf2htmlEX.BackgroundImageFormat.JPG);
+            pdfConverter.setDRM(false);
             pdfConverter.setProcessAnnotation(true);
             if (options.password != null) {
                 pdfConverter.setOwnerPassword(options.password).setUserPassword(options.password);