build: update to C++20

We are using C++20 in all our repositories now.

Change-Id: I6e9c3a125944033f1be0912ce1885565d716d51c
diff --git a/meson.build b/meson.build
index dbc4612..3f08d17 100644
--- a/meson.build
+++ b/meson.build
@@ -4,9 +4,10 @@
     version: '1.0',
     license: 'GPLv2',
     default_options: [
-        'cpp_std=c++17',
+        'cpp_std=c++20',
         'werror=true',
     ],
+    meson_version: '>=0.57.0',
 )
 
 install_data(