meson: update to c++20

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ie01eb0006c75ba753685a98e7357b436b6e7d748
diff --git a/meson.build b/meson.build
index a064c1c..63e5979 100644
--- a/meson.build
+++ b/meson.build
@@ -2,8 +2,9 @@
 
 project('phosphor-debug-collector',
         'cpp',
+        meson_version: '>= 0.57.0',
         default_options: [
-                          'cpp_std=c++17',
+                          'cpp_std=c++20',
                           'warning_level=3',
                           'werror=true',
                           'buildtype=debugoptimized'