devel/libpeas: work around incomplete target dependency

../tests/libpeas/extension-c.c:32:10: fatal error: 'plugins/embedded/embedded-resources.h' file not found
#include "plugins/embedded/embedded-resources.h"

^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

PR: 259080
Reported by: antoine (via exp-run)
Regressed by: https://github.com/mesonbuild/meson/commit/22c38a000673