meson.build: bump version of libudev

It didn't receive new API calls, bit it was changed, hence bump the
version accordingly.

meson.build

@@ -14,7 +14,7 @@ project('systemd', 'c',
        )
 
 libsystemd_version = '0.31.0'
-libudev_version = '1.7.0'
+libudev_version = '1.7.1'
 
 # We need the same data in two different formats, ugh!
 # Also, for hysterical reasons, we use different variable