fix: bump go-eth2-client to v0.1.8 for heze state decoding

[barnabasbusa]

buildoor crash-loops on focil-devnet-0 with failed to decode heze beacon state: the pinned go-eth2-client decodes Heze states with the Gloas types, but Heze adds inclusion_list_bits to ExecutionPayloadBid (EIP-7805), so the offsets are off by two bytes. v0.1.8 has real Heze types and decodes a live lodestar Heze state from focil-devnet-0 cleanly. This bumps it (pulling dynamic-ssz and hashtree-bindings along) and updates TestHandleSubmitBeaconBlock_ProposalVersion to send a real Heze block for the Heze case, since a Gloas-shaped body is now correctly rejected for missing inclusion_list_bits.

[redpandabot]

Dependency bump of go-eth2-client to v0.1.8 (with dynamic-ssz and hashtree-bindings pulled along) to fix Heze beacon state decoding. Verified: OSV is clean for all three new versions, the transitive bumps match go-eth2-client v0.1.8's own requirements exactly, the casbin/govaluate removal is the correct graph change (dynamic-ssz dropped it), and v0.1.8 contains real Heze types with ExecutionPayloadBid.InclusionListBits (ssz-size:"2"). No findings.

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_{Reviewed 2 changed file(s) @ c31cdddc — no blocking issues found.
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