clipboard.zig instead of Clipboard.zig

[tictacmenthe]

https://github.com/Guigui220D/zig-sfml-wrapper/blame/c95fe32eaf2dfce4dec22b63acbd85e338bfd948/src/window/window_module.zig#L8

It sems the file is actually named "clipboard.zig", The capital C seems to prevent compilation on my system currently.
I cannot seem to find why it doesn't work on mine alone.

[Guigui220D]

Hello,
thanks for the issue, yeah I seem to recall that casing is a problem or not depending on the OS... You can make a PR if you want ! Otherwise I'll fix that later
Thanks