Bump executorch's shim copyc c

[bigfootjon]

Summary: I need a newer version of this to merge executorch's TARGETS files into BUCK files.

Differential Revision: D109762646

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/20523

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✅ You can merge normally! (2 Unrelated Failures)

As of commit 2d3088b with merge base 6021a58 ():

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / unittest / windows / windows-job (gh) (trunk failure)
  Process completed with exit code 2.
• pull / unittest-editable / windows / windows-job (gh) (trunk failure)
  Process completed with exit code 2.

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[meta-codesync]

@bigfootjon has exported this pull request. If you are a Meta employee, you can view the originating Diff in D109762646.

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[Copilot]

Pull request overview

This PR bumps the shim git submodule pointer to a newer buck2-shims-meta commit needed to support migrating ExecuTorch TARGETS files into BUCK files.

Changes:

• Update the shim submodule from b295819bb0ec... to eb8ff9d0e443... (commit message: “Add missing file for executorch migration”).

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