`load_cluster_dump` using `msgpack>=1.0` fails with `ValueError: int is not allowed for map key when strict_map_key=True`

**Describe the issue**:

Reading a cluster dump fails.

**Minimal Complete Verifiable Example**:

```python
>>> from distributed.cluster_dump import DumpArtefact
>>> url = "s3://.../dask-root-8ad03e68-6.dump.msgpack.gz"
>>>
>>> dump = DumpArtefact.from_url(url)
Traceback (most recent call last):
File "", line 1, in
File "/usr/local/lib/python3.11/site-packages/distributed/cluster_dump.py", line 140, in from_url
return DumpArtefact(load_cluster_dump(url, **kwargs))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/site-packages/distributed/cluster_dump.py", line 106, in load_cluster_dump
return reader(f)
^^^^^^^^^
File "/usr/local/lib/python3.11/site-packages/msgpack/__init__.py", line 47, in unpack
return unpackb(data, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^
File "msgpack/_unpacker.pyx", line 194, in msgpack._cmsgpack.unpackb
ValueError: int is not allowed for map key when strict_map_key=True
```

**Anything else we need to know?**:

I'm using the same docker image, OS and python dependencies when reading the dump that were used to write it.

**Environment**:

- Dask version: see below
- Python version: 3.11.7
- Operating System: linux
- Install method (conda, pip, source): pip

dask==2023.3.2
dask-kubernetes==2023.3.2
distributed==2023.3.2.1
msgpack==1.0.7