Pectra ready: update accordning to EIP-7251: Increase the MAX_EFFECTIVE_BALANCE

[pavelkrolevets]

Ethereum going to change deposit amount to allow it in range 32 to 2048 ETH eip7251

• updated spec
• new flag amount
• update tests

[pavelkrolevets]

after we merge https://github.com/ssvlabs/dkg-spec/pull/13, we can update go.mod to use ssvlabs/dkg-spec instead of pavelkrolevets/dkg-spec