bump nim-web3 to enable calling getPayload with exact type

[tersec]

This allows nimbus-eth2 to avoid post-hoc validation when it knows entirely

Follow-up to #4465 (comment) #4465 (comment) #4465 (comment)

There are workarounds currently, e.g.,

nimbus-eth2/beacon_chain/eth1/eth1_monitor.nim

Lines 901 to 908 in 6a3dc07

	when payloadFork == ConsensusFork.Capella:
	# TODO: The engine_api module may offer an alternative API where it is guaranteed
	# to return the correct response type (i.e. the rule below will be enforced
	# during deserialization).
	if req.read.executionPayload.withdrawals.isNone:
	warn "Execution client did not return any withdrawals for a post-Shanghai block",
	url = m.elConnections[idx].engineUrl.url
	continue

But migrating nimbus-eth2 to the new API from nim-web3 can avoid these.

[github-actions]

Unit Test Results

         9 files  ±0    1 068 suites  ±0   30m 10s ⏱️ - 2m 31s
  3 648 tests ±0    3 369 ✔️ ±0  279 💤 ±0  0 ❌ ±0 
15 569 runs  ±0  15 264 ✔️ ±0  305 💤 ±0  0 ❌ ±0 

Results for commit 79788a1. ± Comparison against base commit 6539928.