requirements: bump min aiorpcx to 0.22.0

aiorpcx 0.20 changed the behaviour/API of TaskGroups.
When used as a context manager, TaskGroups no longer propagate
exceptions raised by their tasks. Instead, the calling code has
to explicitly check the results of tasks and decide whether to re-raise
any exceptions.
This is a significant change, and so this commit introduces "OldTaskGroup",
which should behave as the TaskGroup class of old aiorpcx. All existing
usages of TaskGroup are replaced with OldTaskGroup.

closes https://github.com/spesmilo/electrum/issues/7446

electrum/address_synchronizer.py

@@ -28,11 +28,9 @@ import itertools
 from collections import defaultdict
 from typing import TYPE_CHECKING, Dict, Optional, Set, Tuple, NamedTuple, Sequence, List
 
-from aiorpcx import TaskGroup
-
 from . import bitcoin, util
 from .bitcoin import COINBASE_MATURITY
-from .util import profiler, bfh, TxMinedInfo, UnrelatedTransactionException, with_lock
+from .util import profiler, bfh, TxMinedInfo, UnrelatedTransactionException, with_lock, OldTaskGroup
 from .transaction import Transaction, TxOutput, TxInput, PartialTxInput, TxOutpoint, PartialTransaction
 from .synchronizer import Synchronizer
 from .verifier import SPV
@@ -193,7 +191,7 @@ class AddressSynchronizer(Logger):
     async def stop(self):
         if self.network:
             try:
-                async with TaskGroup() as group:
+                async with OldTaskGroup() as group:
                     if self.synchronizer:
                         await group.spawn(self.synchronizer.stop())
                     if self.verifier: