Fix Status.im 1.13.0 build
For some incomprehensible reason it fails with:
error: creating directory '/tmp/tmp-status-react-896b583da/nix-shell-900-0': Permission deniedhttps://monitor.f-droid.org/builds/log/im.status.ethereum/2021042608
Since /tmp should always have 1777 permisions this should not
happen, but since it does I'm adding this dirty hack to the config.
Signed-off-by: Jakub Sokołowski jakub@status.im