build: require meson 1.4.0 or newer

This was already the de facto requirement, we use the method `full_path`
on a file object (introduced in Meson 1.4.0) in the functional test
suite's build.

This version of Meson is in NixOS 24.05, so there should be no
compatibility issues should this make it into a backported release of
Lix.

CC: https://git.lix.systems/lix-project/lix/issues/247
Change-Id: I5c640824807353b6eb4287e7ed09c4e89a4bdde2

meson.build

@@ -47,6 +47,7 @@
 # in the build directory.
 
 project('lix', 'cpp', 'rust',
+  meson_version : '>=1.4.0',
   version : run_command('bash', '-c', 'echo -n $(jq -r .version < ./version.json)$VERSION_SUFFIX', check : true).stdout().strip(),
   default_options : [
     'cpp_std=c++2a',