remove last comma and space from sources

app.py

@@ -105,7 +105,7 @@ def get_answer(question):
         unique_pages += str(item) + ", "
 
     # will look like 1, 2, 3,
-    pages = unique_pages[:-1] # removes the last comma
+    pages = unique_pages[:-2] # removes the last comma and space
 
     # source text
     full_source = ""