Upstream libfmt >=11.0 fix; remove deprecated localtime

[nmhare]

Replace deprecated fmt::localtime with common::localtime for fmt 11
Remove guipriv warning text from Qt6.10

[nmhare]

This is the same fix as applied here dolphin-emu#13727

[NikhilNarayana]

is there a specific reason to pull in this commit on its own? i prefer to only do this if there is a breaking issue with builds and to cherry-pick it directly into our branch from upstream

[nmhare]

Yes the 12.0.0 release of libfmt (https://github.com/fmtlib/fmt/releases) deprecated the fmt::localtime() function and caused my build to fail on latest arch, with the error ‘localtime’ is not a member of ‘fmt’. This fixes that error

Let me know if you need any more information

[aurzenith]

Can I ask why your changes differ from the fixes that are merged in the upstream repo? Specifically in TimeUtil.cpp. Also adding in a random CMake warning text change on top of this is a little strange.

[nmhare]

Hello, apologies for confusion, I am new to this. I promise I'm not an AI

Can I ask why your changes differ from the fixes that are merged in the upstream repo? Specifically in TimeUtil.cpp.

I did these changes manually and only changed the capitalization from Localtime to LocalTime, I simply missed TimeUtil.cpp. If pulling these changes in from upstream is proper, please do that.

Also adding in a random CMake warning text change on top of this is a little strange.

This is in response to a recent commit daae8a0 which updated for Qt6.10+. This creates the following warning:

Project MESSAGE: This project is using private headers and will therefore be tied to this specific Qt module build version.
Project MESSAGE: Running this project against other versions of the Qt modules may crash at any arbitrary point.
Project MESSAGE: This is not a bug, but a result of using Qt internals. You have been warned!

Since Slippi is not using any private headers, but only now needs to include the header file, I thought it'd be fine to suppress. I found a similar fix in the RPCS3 repo here https://github.com/RPCS3/rpcs3/pull/17589/files and thought to include this suppression. If this is not recommended or should be in a different PR, I can remove (although maybe pulling in that dolphin commit is better?).

[aurzenith]

There are more changes in the original merged commit that should be added to this.

[aurzenith]

I see, the fix for CMake isn't a bad idea, but typically keep a PR focused on one thing and not add anything unrelated to it. As approving the one part, will also approve the other part, and keeps reviewing easier and cleaner.