Update `xgboost` pinning in dask-sql environments

[charlesbluca]

Looks like the version/build scheme of the RAPIDS xgboost nightlies has changed, which is causing dask-sql image builds to fail - this should unblock.

[jakirkham]

Yep it has. Thanks for the fix. Here's how the xgboost string is constructed

Also here's how the strings are used to constrain xgboost & libxgboost. Note in this case we are constraining XGBoost to get a CUDA enabled version (Idk if that is something we want here)

[charlesbluca]

Thanks for the context @jakirkham! Will make sure to also constrain libxgboost in that case

[charlesbluca]

Noting that the image builds still fail with these changes; it looks like this is because we're still waiting on libxgboost nightlies to be published to correspond with RAPIDS 23.10. However, assuming once those are published we should be fully unblocked