[Proposal] Update Max LTV for bETH

Max LTV for any whitelisted Anchor assets will have a significant effect onto the actual yield for the Nexus vaults. With the recent passing of the vote on raising the max LTV for bETH to 75%, Nexus will stand to benefit from this increased max LTV for bETH.

Propose to raise the LTV ratio of bETH vaults from 45-50% to 60-65% since the max LTV for bETH is 75% as opposed to bLuna at 80%.

Btw, I think we should have a Nexus template for proposals.