prophet.serialize FutureWarning: The behavior of Timestamp.utcfromtimestamp is deprecated...

I apologise if this is duplicated somewhere else, but I couldn't find a similar issue. When loading a saved prophet model with `prophet.serialize.model_from_json`, I get a warning in the console:

```
C:\ProgramData\Anaconda3\envs\flaskapp-env\lib\site-packages\prophet\serialize.py:172: FutureWarning:

The behavior of Timestamp.utcfromtimestamp is deprecated, in a future version will return a timezone-aware Timestamp with UTC timezone. To keep the old behavior, use Timestamp.utcfromtimestamp(ts).tz_localize(None). To get the future behavior, use Timestamp.fromtimestamp(ts, 'UTC')
```

Just wondering if this is a known issue, or whether its to do with the versions of prophet, pandas or python I have.
```
prophet=1.1.5
pandas=1.5.3
python=3.9.17
```