Serve .wasm artifacts with the `application/wasm` MIME type

It is not possible to load .wasm artifacts directly, since they aren’t served with the correct MIME type (application/wasm), which is enforced by (at least) Firefox and Chromium.

Here’s the relevant part of the WebAssembly spec: https://www.w3.org/TR/wasm-web-api-1/#streaming-modules

And here’s an issue for the specific case I’m running into: https://github.com/iodide-project/pyodide/issues/174

Can you expand on this to include a question about CircleCI? :smiley_cat:

This relates to .wasm files served as Circle CI artifacts. At the moment, they are not loadable directly into a webbrowser because they have the wrong MIME type.