--chromium not to require args

I've modified the --chromium argument to be enough in itself to provide 'True' with no need to add CLI argument to it.

scraper/scraper.py

@@ -874,6 +874,8 @@ if __name__ == "__main__":
     )
     ap.add_argument(
         "--chromium",
+        nargs='?',
+        const=True,
         help="Should I use Chromium instead?",
         default=False
     )