gh-92626: Correct JavaScript MIME types + extensions per RFC 9239 by mathiasbynens · Pull Request #92627 · python/cpython

This patch updates the MIME type configuration per RFC 9239.
https://www.rfc-editor.org/rfc/rfc9239

First, the recommended MIME type is now `text/javascript`:

> The most widely supported media type in use is `text/javascript`; all
> others are considered historical and obsolete aliases of `text/javascript`.

Second, the `.mjs` extension is now explicitly registered:

> The `.mjs` file extension signals that the file represents a JavaScript
> module. Execution environments that rely on file extensions to
> determine how to process inputs parse `.mjs` files using the Module
> grammar of [ECMA-262].

IANA template: https://www.iana.org/assignments/media-types/text/javascript