update pin to 2/29

Summary:
Updating pin to 2/29 to use new APIs from ExportedProgram
Introduced here:
https://github.com/pytorch/pytorch/pull/120546

pull request: https://github.com/pytorch/executorch/pull/2160

bypass-github-export-checks
bypass-github-pytorch-ci-checks
bypass-github-executorch-ci-checks

Reviewed By: mergennachin

Differential Revision: D54314206

fbshipit-source-id: d844ca46a5dc0c68ce5e6d8cf7e311982c26a8d7