meson: Update minimum version to 0.57.0

Required for c++20 suppport.

Change-Id: I3d34c7ebecbb9b7a1f1f8fe43f7b36f8d1581979
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/meson.build b/meson.build
index bacc792..ebf6126 100644
--- a/meson.build
+++ b/meson.build
@@ -2,7 +2,7 @@
   'sdeventplus',
   'cpp',
   version: '0.1',
-  meson_version: '>=0.53.2',
+  meson_version: '>=0.57.0',
   default_options: [
     'warning_level=3',
     'cpp_std=c++17',