nix: zscaler — bump zscaler-docker for session persistence

Point the zscaler-docker flake input at 02c475c, which keeps the container
across `zscaler down`/`up` so the Okta login persists between reconnects
(and adds the `recreate` command to start fresh on demand).

🤖 Generated with [eca](https://eca.dev)

Co-Authored-By: eca-agent <git@eca.dev>

Author: ericdallo