SkinnedMesh doesnt work on a 2D setup

## Bevy version

Using the `0.15.0` crates.io release

## \[Optional\] Relevant system information

Not relevant but:

`SystemInfo { os: "Linux 22.04 Pop!_OS", kernel: "6.9.3-76060903-generic", cpu: "AMD Ryzen 9 7940HS w/ Radeon 780M Graphics", core_count: "8", memory: "58.7 GiB" }`
`AdapterInfo { name: "AMD Radeon RX 7700S (RADV NAVI33)", vendor: 4098, device: 29824, device_type: DiscreteGpu, driver: "radv", driver_info: "Mesa 24.0.3-1pop1~1711635559~22.04~7a9f319", backend: Vulkan }`

## What you did

Attempted to implement `SkinnedMesh` and also modified [this example](https://bevyengine.org/examples/animation/custom-skinned-mesh/) to work in 2D

## What went wrong

- what were you expecting?

I was expecting the mesh to deform even just the slightest.

- what actually happened?

When rendering with the 2D camera and using 2D meshes, `SkinnedMesh` doesn't appear to work, but the moment I translated all of my code into 3D it started working.

## Additional information

Could provide more context if really needed or post the above example in 2D.

The linked custom-skinned-mesh example is the only entry point mentioned. Start by comparing its working 3D setup with the reported 2D camera and mesh setup, then reduce the difference to a reproducible case. Done means SkinnedMesh visibly deforms when rendered with a 2D camera and 2D meshes.

Written by the indexing model from the issue text.