Fix `is_url('https://ultralytics.com')` (#9610)

utils/downloads.py

@@ -21,7 +21,7 @@ def is_url(url, check=True):
     try:
         url = str(url)
         result = urllib.parse.urlparse(url)
-        assert all([result.scheme, result.netloc, result.path])  # check if is url
+        assert all([result.scheme, result.netloc])  # check if is url
         return (urllib.request.urlopen(url).getcode() == 200) if check else True  # check if exists online
     except (AssertionError, urllib.request.HTTPError):
         return False