[utils] Add `Sec-Fetch-Mode` to `std_headers`

Closes #2187

yt_dlp/utils.py

@@ -145,6 +145,7 @@ std_headers = {
     'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
     'Accept-Encoding': 'gzip, deflate',
     'Accept-Language': 'en-us,en;q=0.5',
+    'Sec-Fetch-Mode': 'same-origin',
 }