Use consensus-spec-tests v1.3.0-rc.3 (#4021)

## Issue Addressed

NA

## Proposed Changes

Updates our `ef_tests` to use: https://github.com/ethereum/consensus-specs/releases/tag/v1.3.0-rc.3

This required:

- Skipping a `merkle_proof_validity` test (see #4022)
- Account for the `eip4844` tests changing name to `deneb`
    - My IDE did some Python linting during this change. It seemed simple and nice so I left it there.

## Additional Info

NA

testing/ef_tests/src/handler.rs

@@ -650,6 +650,11 @@ impl<E: EthSpec + TypeName> Handler for MerkleProofValidityHandler<E> {
 
     fn is_enabled_for_fork(&self, fork_name: ForkName) -> bool {
         fork_name != ForkName::Base
+            // Test is skipped due to some changes in the Capella light client
+            // spec.
+            //
+            // https://github.com/sigp/lighthouse/issues/4022
+            && fork_name != ForkName::Capella
     }
 }