trivial: Fix a small memory leak in the new FuContext code
trivial: Fix a small memory leak in the new FuContext code

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=33155

fwupd/fwupd,hughsie/fwupd,fwupd/fwupd,fwupd/fwupd,hughsie/fwupd,hughsie/fwupd,fwupd/fwupd,hughsie/fwupd