build: switch to C++20

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ifb2971a421845a75e5b8f2e55da73db5f93897ec
diff --git a/meson.build b/meson.build
index 696bc87..86a1d71 100644
--- a/meson.build
+++ b/meson.build
@@ -4,10 +4,11 @@
     default_options: [
         'warning_level=3',
         'werror=true',
-        'cpp_std=c++17'
+        'cpp_std=c++20'
     ],
     license: 'Apache-2.0',
     version: '1.0',
+    meson_version: '>=0.57.0',
 )
 
 # Wno-psabi reduces the number of "Note:" messages when cross-compiling some STL