Fix CI builds for macos (#178)

Summary:
The macos builds were broken (e.g., [this](https://github.com/facebookincubator/momentum/actions/runs/12601246229/job/35121997468)) due to recent the abseil package update. Now that the issues are fixed by conda-forge/abseil-cpp-feedstock#88 and conda-forge/abseil-cpp-feedstock#90, we fix it by simply updating the `pixi.lock` file.
## Checklist:

- [x] Adheres to the [style guidelines](https://facebookincubator.github.io/momentum/docs/developer_guide/style_guide)
- [x] Codebase formatted by running `pixi run lint`

Pull Request resolved: #178

Test Plan: CI

Reviewed By: juliencbmeta

Differential Revision: D67865721

Pulled By: jeongseok-meta

fbshipit-source-id: d5526c0ecac56b57297deff516313f3fbc7aad71