Increase MaxValidators to 80

As discussed here: https://forum.akash.network/t/proposal-further-increase-the-maximum-validators-parameter-and-decentralisation/632 and building on https://www.mintscan.io/akash/proposals/7 2 and https://forum.akash.network/t/proposal-increase-of-max-validators-cap/73 this is a new proposal to further increase the maximum validators parameter and thus the decentralisation of the network based on the amount of competent validators currently in the inactive set.