compiling and working for zig 0.14.1

[corymonroe]

The most minimal PR to get Mini Pixel working for Zig 0.14.1. A couple notes:

• Compiles and runs in Release modes for Linux and Windows.
• The debug build crashes due to a panic in SDL mouse gesture handling. A square root function is performed which left shifts wider than the width of the value being shifted. I think this is just the Zig compiler catching undefined behavior in SDL2. This only happens on my Windows Desktop. It's unclear if its windows specific or hardware specific...
• There seems to be a strange lerping behavior with the mouse. For example, if I click an open widget, move the mouse to the file dialog and cancel, the mouse lerps between the two positions after clicking cancel.
• I have to add the vcpkg directories directly as vcpkg install does not put the libs in any known env:path for me. I don't think that should harm the builds that rely on a system install of libpng.

I'd like to fix the above issues as well as clean up some of the dependencies but I think it might be best to keep this PR as minimal as possible.

If you want anything at all changed or see anything wrong let me know. Would love to get this merged!

Thanks for the awesome piece of software!

[corymonroe]

One small change to get it working on Linux. Linux build does not seem to have any of the above issues listed in the description.