Support UInt8Array data in response

[Poitrin]

Next.js 12.1 SSR delivers response data in UInt8Array format. In Node.js both string and UInt8Array are supported in function signature. See https://nodejs.org/dist/latest-v16.x/docs/api/buffer.html#static-method-bufferfrombuffer

This got fixed with dougmoscrop/serverless-http#232

As serverless-express’s src/response.js is based on serverless-http (see ATTRIBUTION in line 1), this might just be a simple copy-paste :-)

[Poitrin]

Thanks to PR #540 and the latest serverless-express version, this issue has been solved.
Big thank you to @H4ad and @brett-vendia for the quick fix :-)