test_closing: Increase feerate test limit

When running test_closing.py `test_peer_anchor_push` in a loop, it failed on the 43rd time with the error:

actual_feerate = 12005.233318796338, expected_feerate = 12000

Increasing the expected feerate fixes this particular flake.

Changelog-None

Author: ddustin

tests/test_closing.py

@@ -4052,7 +4052,7 @@ def test_peer_anchor_push(node_factory, bitcoind, executor, chainparams):
     wait_for(lambda: len(bitcoind.rpc.getrawmempool()) == 2)
 
     # As blocks pass, we will use anchor to boost l3's tx.
-    for block, feerate in zip(range(120, 124), (12000, 13000, 14000, 15000)):
+    for block, feerate in zip(range(120, 124), (12010, 13000, 14000, 15000)):
         l2.daemon.wait_for_log(fr"Worth fee [0-9]*sat for remote commit tx to get 100000000msat at block 125 \(\+{125 - block}\) at feerate {feerate}perkw")
         l2.daemon.wait_for_log("sendrawtx exit 0")
         # Check feerate for entire package (commitment tx + anchor) is ~ correct