Authorize the upgrade to zeitgeist-runtime v0.4.0 (spec_version 49)

https://github.com/zeitgeistpm/zeitgeist/releases/tag/v0.4.0

Schedule a majority-carries referendum to be tabled next once it is legal to schedule
an external referendum.

The dispatch of this call must be `ExternalMajorityOrigin`.

- `proposal_hash`: The preimage hash of the proposal.

Unlike `external_propose`, blacklisting has no effect on this and it may replace a
pre-scheduled `external_propose` call.

Weight: `O(1)`

- Problem Statement: Upgrading to zeitgeist-runtime v0.4.0 (spec_version 49) for the Polkassembly Council.
- Significance: Enhancing the functionality and performance of the Polkassembly Council platform.
- Proposed Solution: Authorizing the upgrade to zeitgeist-runtime v0.4.0.
- Expected Outcomes: Improved platform functionality and performance for the Polkassembly Council.

#36 Upgrade to v0.4.0 (spec_version 49)