Replace deprecated append() with concat()

app.py

@@ -70,7 +70,7 @@ def find_sentences(query, hits):
                     "Text": corpus[corpus_id][:80],
                     "Score": "{:.2f}".format(hit["score"]),
                 }
-		output = pd.concat([output, pd.DataFrame([new_row])], ignore_index=True)
+                output = pd.concat([output, pd.DataFrame([new_row])], ignore_index=True)
                 break
     return output