Restrict fullscreen=() in Permissions-Policy to match restrictive approach for all APIs

Agent-Logs-Url: https://github.com/xtekky/gpt4free/sessions/bf9b023a-6921-41be-b964-7b245db2fb4f

Co-authored-by: hlohaus <983577+hlohaus@users.noreply.github.com>

g4f/api/__init__.py

@@ -963,7 +963,7 @@ class Api:
                 # Restrict powerful browser APIs that workspace pages don't need
                 "Permissions-Policy": (
                     "geolocation=(), camera=(), microphone=(), "
-                    "payment=(), usb=(), fullscreen=self"
+                    "payment=(), usb=(), fullscreen=()"
                 ),
                 "Cache-Control": "no-store",
             }