pytest: give test_xpay_maxfee longer, as it can time out under CI.

```
>       ret = l1.rpc.xpay(invstring=inv, maxfee=maxfee)

tests/test_xpay.py:585: 
...
>           raise RpcError(method, payload, resp['error'])
E           pyln.client.lightning.RpcError: RPC call failed: method: xpay, payload: {'invstring': 'lnbcrt1m1p5n5wdzsp5qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqpp52mu6842a26hs40xxgzscflm4smk5yjctqgf7hhrwhx7dh2492vzsdp22pshj6twvusxummyv5sr2wfqwa5hg6pqd4shsen9v5cqpj9qyyqqqj9kvjvrzy0ygdsfsskjtss0xrkrt7lq8jyrgzvtvdw5y9xqy0v25ddxd787c9ym36udm876lyhevznj8j9qzk0r7x03xm0akvq6ltwcq7vm7tk', 'maxfee': 57966}, error: {'code': 209, 'message': "Failed after 4 attempts. We got temporary_channel_failure for 59x81x28707/1, assuming it can't carry 49498813msat. Then routing for remaining 49498813msat failed: linear_routes: timed out after deadline"}
...
lightningd-1 2025-12-11T03:25:41.972Z DEBUG   plugin-cln-askrene: notify msg debug: get_routes failed after 15572 ms
```

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Author: rustyrussell

tests/test_xpay.py

@@ -557,7 +557,9 @@ def test_xpay_maxfee(node_factory, bitcoind, chainparams):
                                      opts=[{'gossip_store_file': outfile.name,
                                             'subdaemon': 'channeld:../tests/plugins/channeld_fakenet',
                                             'allow_warning': True,
-                                            'dev-throttle-gossip': None},
+                                            'dev-throttle-gossip': None,
+                                            # This can be more than 10 seconds under CI!
+                                            'askrene-timeout': 60},
                                            {'allow_bad_gossip': True}])
 
     # l1 needs to know l2's shaseed for the channel so it can make revocations