Crash from WhoAreYou nonce mismatch

## What was wrong?

Crash from this exception

```
Traceback (most recent call last):
File "/home/piper/python-environments/ddht/bin/ddht", line 33, in
sys.exit(load_entry_point('ddht', 'console_scripts', 'ddht')())
File "/home/piper/projects/ddht/ddht/_boot.py", line 59, in _boot
trio.run(manager.run)
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/trio/_core/_run.py", line 1896, in run
raise runner.main_task_outcome.error
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/trio.py", line 183, in run
self._total_task_count = 0
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/trio/_core/_run.py", line 741, in __aexit__
raise combined_error_from_nursery
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/base.py", line 324, in _run_and_manage_task
await task.run()
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/trio.py", line 76, in run
await self._async_fn(*self._async_fn_args)
File "/home/piper/projects/ddht/ddht/_boot.py", line 27, in run
await _main()
File "/home/piper/projects/ddht/ddht/_boot.py", line 13, in _main
await main()
File "/home/piper/projects/ddht/ddht/main.py", line 54, in main
await args.func(args, boot_info)
File "/home/piper/projects/ddht/ddht/cli_commands.py", line 28, in do_main
await manager.wait_finished()
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_generator/_util.py", line 42, in __aexit__
await self._agen.asend(None)
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/trio.py", line 411, in background_trio_service
await manager.stop()
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/trio/_core/_run.py", line 741, in __aexit__
raise combined_error_from_nursery
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/trio.py", line 183, in run
self._total_task_count = 0
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/trio/_core/_run.py", line 741, in __aexit__
raise combined_error_from_nursery
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/base.py", line 324, in _run_and_manage_task
await task.run()
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/base.py", line 169, in run
await self.child_manager.run()
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/trio.py", line 183, in run
self._total_task_count = 0
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/trio/_core/_run.py", line 741, in __aexit__
raise combined_error_from_nursery
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/base.py", line 324, in _run_and_manage_task
await task.run()
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/base.py", line 169, in run
await self.child_manager.run()
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/trio.py", line 205, in run
raise trio.MultiError(
trio.MultiError: DaemonTaskExit('Daemon task EnvelopeDecoder[daemon=True] exited'), HandshakeFailure('WhoAreYou packet nonce does not match request nonce: expected=75306c5a6de6549d837283b0 actual=0000000563e7f4cf73e58468')

Details of embedded exception 1:

Traceback (most recent call last):
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/base.py", line 324, in _run_and_manage_task
await task.run()
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/base.py", line 172, in run
raise DaemonTaskExit(f"Daemon task {self} exited")
async_service.exceptions.DaemonTaskExit: Daemon task EnvelopeDecoder[daemon=True] exited

Details of embedded exception 2:

Traceback (most recent call last):
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/base.py", line 324, in _run_and_manage_task
await task.run()
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/base.py", line 169, in run
await self.child_manager.run()
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/trio.py", line 205, in run
raise trio.MultiError(
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/base.py", line 324, in _run_and_manage_task
await task.run()
File "/home/piper/python-environments/ddht/lib/python3.8/site-packages/async_service/trio.py", line 76, in run
await self._async_fn(*self._async_fn_args)
File "/home/piper/projects/ddht/ddht/v5_1/dispatcher.py", line 162, in _handle_inbound_envelopes
was_handled |= await session.handle_inbound_envelope(envelope)
File "/home/piper/projects/ddht/ddht/v5_1/session.py", line 316, in handle_inbound_envelope
) = await self._receive_handshake_response(
File "/home/piper/projects/ddht/ddht/v5_1/session.py", line 363, in _receive_handshake_response
raise HandshakeFailure(
ddht.exceptions.HandshakeFailure: WhoAreYou packet nonce does not match request nonce: expected=75306c5a6de6549d837283b0 actual=0000000563e7f4cf73e58468
```

## How can it be fixed?

Looks like simple error handling.