Fix skybox example crashing in WASM by skipping unsupported TAA

[it-me-joda]

Objective

• Fixes #21731
• Resolve the skybox example not functioning as intended. Currently, the skybox example compiles but can't run due to TAA not being supported for WASM builds.

Solution

• Skip TAA if in a building for a WASM environment.

Testing

• I ran the skybox example locally with: bevy run --example skybox --features="free_camera" web and the example now compiles and runs in the browser.