Merge pull request #3768 from etan-status/at-stability

EIP-7549: Append new `committee_bits` field to end of `Attestation`

Author: hwwhww

specs/electra/beacon-chain.md

@@ -277,8 +277,8 @@ class AttesterSlashing(Container):
 class Attestation(Container):
     aggregation_bits: Bitlist[MAX_VALIDATORS_PER_COMMITTEE * MAX_COMMITTEES_PER_SLOT]  # [Modified in Electra:EIP7549]
     data: AttestationData
-    committee_bits: Bitvector[MAX_COMMITTEES_PER_SLOT]  # [New in Electra:EIP7549]
     signature: BLSSignature
+    committee_bits: Bitvector[MAX_COMMITTEES_PER_SLOT]  # [New in Electra:EIP7549]
 ```
 
 #### `IndexedAttestation`