[cookies] Containers JSON should be opened as utf-8 (#7800)

Closes #7797
Authored by: bashonly

yt_dlp/cookies.py

@@ -138,7 +138,7 @@ def _extract_firefox_cookies(profile, container, logger):
         containers_path = os.path.join(os.path.dirname(cookie_database_path), 'containers.json')
         if not os.path.isfile(containers_path) or not os.access(containers_path, os.R_OK):
             raise FileNotFoundError(f'could not read containers.json in {search_root}')
-        with open(containers_path) as containers:
+        with open(containers_path, encoding='utf8') as containers:
             identities = json.load(containers).get('identities', [])
         container_id = next((context.get('userContextId') for context in identities if container in (
             context.get('name'),