Fixes omni.physx.stageupdate dependency (#466)

# Description

omni.physx.stageupdate is no longer available in the internal registry.
we now switch to using omni.physics.stageupdate instead.

## Type of change

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applicable. -->

- Bug fix (non-breaking change which fixes an issue)

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [ ] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

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apps/isaaclab.python.kit

@@ -89,7 +89,7 @@ keywords = ["experience", "app", "usd"]
 "omni.kit.window.stage" = {}
 "omni.kit.window.status_bar" = {}
 "omni.kit.window.toolbar" = {}
-"omni.physx.stageupdate" = {}
+"omni.physics.stageupdate" = {}
 "omni.rtx.settings.core" = {}
 "omni.uiaudio" = {}
 "omni.usd.metrics.assembler.ui" = {}