Turn Monthly Mini-Hacks into Quarterly events

We'd like to have these recurring events with a quarterly cadence instead of a monthly one, as it'll better optimise the attention necessary from Token Holders to check up and vote on all submissions.

Essentially, this proposal would convert the ongoing 2nd Round of Mini-Hacks into a 3-month event that would last from April until the end of June (Q2 2021). 3rd Round of mini hacks would take place in Q3 2021, and so on.

Similarly, we'd like to increase the total rewards for each round, from 20 W3API per month, to 60 W3API per quarter.

Previous proposal that initiated the mini-hacks initiative can be seen here: https://snapshot.org/#/web3-api/proposal/Qmcj5dKTv8dbCTvnCtc86431MF3PFpaFhtp1kr4hD8WUGf