item.pop("partition") leads to KeyError after retry

[Zaczero]

https://github.com/stac-utils/pgstac/blob/13b7d8d3b4d2897d5450cf92d10910d40b4c4803/src/pypgstac/src/pypgstac/load.py#L329C29-L329C50

This piece of code mutates data in place, and after the first @retry, when #363 is fixed, this will lead to a KeyError because partition was already popped. I also don't see much reason for mutating this data.