Auto merge of #149037 - alexcrichton:update-wasi-sdk, r=jieyouxu

Update wasm-related dependencies in CI

* Update to wasi-sdk-29 released today
* Update to Wasmtime 38.0.4 which was released a week or so ago

This is the same as rust-lang/rust#148611, except with wasi-sdk-29 to fixup some issues found in wasi-sdk-28.

Author: bors