Setup custom values in header not work.

[TiagoSAmaral]

Describe the bug
I try setup the header of request, with the value content-type with application/json, but this not working in browser. This is removed from header.

No value is accepted with the content-type key. I saw in the implementation that the content-type is removed, having a comment:

http/src/request.ts

Line 102 in 27dc4c8

headers.delete('content-type'); // content-type will be set by `window.fetch` to includy boundary

To Reproduce
To reproduce, try setup a post request, and did set header with value: content-type: application/json.

Expected behavior
Expect that { content-type: application/json } reaches the server.

Desktop (please complete the following information):

Im develop a ionic application using Ionic 6, with Capacitor V3. Runing application with command:
ionic serve --lab

• OS: macOS Monterey
• Browser Chrome
• Version 101.0.4951.64