build: upgrade to C++23

Meson 1.1.1 and GCC-13 both support C++23 and a sufficient portion of
the standard has been implemented.  Upgrade the build to leverage it.

Change-Id: If2d8b15b09c85f6c1e7ffa7a25dad8172830f52f
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/meson.build b/meson.build
index 651089b..7b10cbd 100644
--- a/meson.build
+++ b/meson.build
@@ -2,10 +2,10 @@
   'stdplus',
   'cpp',
   version: '0.1',
-  meson_version: '>=0.63.0',
+  meson_version: '>=1.1.1',
   default_options: [
     'warning_level=3',
-    'cpp_std=c++20',
+    'cpp_std=c++23',
     'tests=' + (meson.is_subproject() ? 'disabled' : 'auto'),
     'examples=' + (meson.is_subproject() ? 'false' : 'true'),
   ])