At the request of Parity's Parachains Core team, this updates the `no_show_slots` configuration from `2` to `3`.

This increase provides more time for validators to fetch a PoV and run the parachain validation function in adverse network conditions. Increasing the no show time limit reduces the number of missed approvals and will reduce the load on the network.

Requires whitelist by https://kusama.subsquare.io/fellowship/referendum/44

:

1. This ReferendumV2 post updates the `no_show_slots` configuration from `2` to `3`, as requested by Parity's Parachains Core team. 
2. The increase provides more time for validators to fetch a PoV and run parachain validation function in adverse network conditions.
3. The change should reduce the number of missed approvals and correspondingly lessen the burden on the network. 
4. The proposed change requires whitelist approval by Kusama.

#232 [Whitelisted Caller] Referendum #232: Update Parachain Validation No Show Slots