meson: Switch to C++20

Switch to using the C++20 standard when compiling libcamera.

Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Acked-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

meson.build

@@ -6,7 +6,7 @@ project('libcamera', 'c', 'cpp',
     default_options : [
         'werror=true',
         'warning_level=2',
-        'cpp_std=c++17',
+        'cpp_std=c++20',
     ],
     license : 'LGPL 2.1+')