KeyEvent modifier inconsistent for capital letters

[extrawurst]

Describe the bug
As discussed in the Discord: I observed that on *nix platforms the KeyEvent of a capital letter does not contain the Shift modifier and on Windows it does.

To Reproduce

run the example event-poll-read and press a capital letter (e.g Shift+D)

on mac:

Event::Key(KeyEvent { code: Char('D'), modifiers: NONE })

on windows (cmd.exe and PowerShell)

Event::Key(KeyEvent { code: Char('D'), modifiers: SHIFT })

Expected behaviour
The same consistent behaviour, not sending the Shift-Modifier.