Pin Emscripten (#5100)
Pin Emscripten (#5100)

The current CI breakage is due to
https://github.com/emscripten-core/emscripten/pull/17948. Pin the Emscripten
version used in CI until that can be investigated and resolved.
WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen