meson: Update minimum version to 0.57.0

Required for c++20 suppport.

Change-Id: If50d094a1ed68a5fbe5a5383e0840efea3eb64eb
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/meson.build b/src/meson.build
index b66fec2..a169421 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -2,12 +2,14 @@
 
 fmt_dep = dependency('fmt', required: false)
 if not fmt_dep.found()
+  fmt_opts = import('cmake').subproject_options()
+  fmt_opts.add_cmake_defines({
+    'CMAKE_POSITION_INDEPENDENT_CODE': 'ON',
+    'MASTER_PROJECT': 'OFF',
+  })
   fmt_proj = import('cmake').subproject(
     'fmt',
-    cmake_options: [
-      '-DCMAKE_POSITION_INDEPENDENT_CODE=ON',
-      '-DMASTER_PROJECT=OFF'
-    ],
+    options: fmt_opts,
     required: false)
   assert(fmt_proj.found(), 'fmtlib is required')
   fmt_dep = fmt_proj.dependency('fmt')