build: switch to C++20

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I96e1c035f3fe151c63ac1fd8cef2d5257be419d9
diff --git a/meson.build b/meson.build
index 886f837..38e7abd 100644
--- a/meson.build
+++ b/meson.build
@@ -4,17 +4,18 @@
     default_options: [
         'warning_level=3',
         'werror=true',
-        'cpp_std=c++17',
+        'cpp_std=c++20',
         'buildtype=debugoptimized',
         'b_ndebug=if-release',
     ],
     license: 'Apache-2.0',
     version: '1.0',
+    meson_version: '>=0.57.0',
 )
 add_project_arguments('-Wno-psabi', language: 'cpp')
 
-if get_option('cpp_std') != 'c++17'
-    error('This project requires c++17')
+if get_option('cpp_std') != 'c++20'
+    error('This project requires c++20')
 endif
 
 if(get_option('buildtype') == 'minsize')