Update app.py

app.py

@@ -15,7 +15,7 @@ def download_pdf(url):
 def get_doi(pdf_path):
     pdf2doi.config.set('verbose', False)
     results = pdf2doi.pdf2doi(pdf_path)
-    validation_info = json.loads(str(results['validation_info']))
+    validation_info = results['validation_info']  # Already a dict
     doi = validation_info.get('DOI', None)
     title = validation_info.get('title', None)
     url = validation_info.get('URL', None)