The call in this referenda updates the `safeXcmVersion` of Polkadot System Parachains to value 3.

Currently set version 2 is outdated and will be deprecated. Setting this to version 3 is required to support new V3 destinations/connections by default.

Note: Polkadot Relay already has this set to 3 so that's why it's not included in the call.

Needs to be whitelisted by: https://collectives.polkassembly.io/referenda/77