fix: Set default http3=False for ImpitHttpClient (apify#1685)

### Description

- Set default `http3=False` for `ImpitHttpClient`.Since in some cases
the `http3=True` flag causes the proxy to be ignored

### Issues

- Closes: apify#1683

Author: Mantisus

src/crawlee/http_clients/_impit.py

@@ -92,7 +92,7 @@ def __init__(
         self,
         *,
         persist_cookies_per_session: bool = True,
-        http3: bool = True,
+        http3: bool = False,
         verify: bool = True,
         browser: Browser | None = 'firefox',
         **async_client_kwargs: Any,