Remove RestrictNamespaces from systemd service
libcamera uses namespaces to sandbox IPA (Image Processing Algorithm) modules because they are sometimes proprietary binary blobs. The RestrictNamespaces option in Wireplumber's systemd service breaks this sandboxing when libcamera is loaded via the libcamera SPA module, so cameras requiring an IPA do not work.
This commit removes RestrictNamespaces so that the sandboxing works again. I've confirmed that after this change wireplumber works with libcamera with an IPA module.
Resolves #466 (closed)