Update Emscripten to v3.1.1.#133

PiotrSikora merged 4 commits intoproxy-wasm:masterproxy-wasm/proxy-wasm-cpp-sdk:masterfrom

PiotrSikora:emsdk_v3.1.1-old_toolchainPiotrSikora/proxy-wasm-cpp-sdk:emsdk_v3.1.1-old_toolchainCopy head branch name to clipboard