Fix: redirect reg.exe error to null

1 job for wsl_native_qemu_auto in 10 minutes and 23 seconds (queued for 2 seconds)
Name Stage Failure
img Test
Installing package vim
* Failure 404 Not Found
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Custom { kind: NotFound, error: " not found" }', /builds/kITerE/redox/installer/src/
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
make[1]: Leaving directory '/builds/kITerE/redox'
make[1]: *** [mk/ build/filesystem.bin] Error 101
make: *** [Makefile:69: ci-img] Error 2
Cleaning up file based variables
ERROR: Job failed: exit code 1