Add support for optimism

[jdestephen]

Add support for optimistic ethereum and optimistic kovan

[ivanzhelyazkov]

Any update on this ? Currently using the package and it works flawlessly for all networks, but still no support for optimism.
@cavanmflynn @tobowers @guotie

[damianmarti]

I just opened a PR to add Optimism support!

[0xmichalis]

For anyone who is interested to use this library w/ Optimism support, I have temporarily forked to @kargakis/ethers-multicall until #40 gets merged.

[thibauld]

Is there anything preventing the merge of the Optimism support PR? I'd be interested too :)