Bump SSZ version for larger bitfield SmallVec

[paulhauner]

Issue Addressed

NA

Proposed Changes

Bumps the ethereum_ssz version, along with other crates that share the dep.

Primarily, this give us bitfields which can store 128 bytes on the stack before allocating, rather than 32 bytes (sigp/ethereum_ssz#38). The validator count has increase massively since we set it at 32 bytes, so aggregation bitfields (et al) now require a heap allocation. This new value of 128 should get us to ~2m active validators.

Additional Info

• Bitfields have been moved from ssz_types to ethereum_ssz, so there's some non-substantial changes to error handling.
• The MetaData struct in lighthouse_network holds two bitfields and therefore now has a larger stack size. I had to Arc it to avoid some clippy lints about disparate enum sizes.