meson: Update minimum version to 0.57.0

Required for c++20 suppport.

Change-Id: Ida3bdf9615505f7fcc360f5dd246fda5066d6ba5
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/example/meson.build b/example/meson.build
index b437a7d..de1cc6b 100644
--- a/example/meson.build
+++ b/example/meson.build
@@ -5,5 +5,5 @@
 foreach example : examples
   executable(example, example + '.cpp',
              implicit_include_directories: false,
-             dependencies: gpioplus)
+             dependencies: gpioplus_dep)
 endforeach