chore: update ref-fvm to v4.7.3

[rjan90]

Brings in the ref-fvm bump here: filecoin-project/ref-fvm#2203, which was created because filecoin-proofs-api was bump from 18.1.0 to 19.0.0 there, and it would be nice to align it there, since it already has been bumped here: #536

[Copilot]

Pull Request Overview

This PR updates the ref-fvm dependency from version 4.7.2 to 4.7.3 and removes the "nv27-dev" feature flag from the fvm4 package configuration.

• Updates fvm4 and fvm4_shared package versions from ~4.7.2 to ~4.7.3
• Removes the "nv27-dev" feature from fvm4 package dependencies

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}