Upgrade spec to 1.3.0-rc.4 with deneb and fork choice tests skipped to be enabled in followups#5278

twoeths merged 3 commits intounstableChainSafe/lodestar:unstablefrom

g11tech/v1.3.0-rc.4ChainSafe/lodestar:g11tech/v1.3.0-rc.4Copy head branch name to clipboard