Need to capture parcels git sha used in tests

At the moment, we use `Pixi` to bring in Parcels from a dev channel via conda. It would be nice to be able to pull in a specific version of Parcels from the github.com/parcels-code/parcels repository. Additionally, when running the benchmark, we want to be able to record an identifiable version (e.g. git sha) of parcels that was used for the benchmarks and record it in the benchmark entry.

