Sometimes the `src-tauri/` project gets out of date Cargo.lock. This
adds a CI check to prevent it.
This can happen because `src-tauri` is a separate Cargo project from
`src/wasm-lib`, but the former includes the latter as a dependency. So,
when wasm-lib updates a dep (e.g. bump databake from 1.7 to 1.8), the
former will, upon recompilation, pull in the newer databake dep. But
programmers in the wasm-lib repo don't usually work in the src-tauri repo
and so the src-tauri repo doesn't get updated.
50fcdff879