Remove version from DDG bangs url

Including the version portion of the URL now redirects to search results
for the name of the bang file, rather than returning the bang file
itself. Removing the version from the URL returns the correct bang file.

app/utils/bangs.py

@@ -2,7 +2,7 @@ import json
 import requests
 import urllib.parse as urlparse
 
-DDG_BANGS = 'https://duckduckgo.com/bang.v255.js'
+DDG_BANGS = 'https://duckduckgo.com/bang.js'
 
 
 def gen_bangs_json(bangs_file: str) -> None: