Add sepolia alternatives

[rin-st]

We have a problem with gas fees on Sepolia and people ask to add support of other testnets.

I think we need to add support for arbitrumSepolia, optimismSepolia, polygonAmoy (polygonMumbai is deprecated), and baseSepolia.

Steps:

1. Add verification for contracts on these networks. It's required for downloading contracts code, we need it for auto-grader. Upgrade all the challenges. Challenge 0 PR (will be changed to base-challenge-template branch and then merged to others): Challenge 0: update readme for support OP sepolia #214
2. Update SRE repo to support new testnets More testnests support BuidlGuidl/SpeedRunEthereum#209
3. Update auto-grader to support new testnets More testnets support austintgriffith/speedrun-grader#10

2 and 3 should be merged almost at the same time since APIs are updated. I think I can add backward compatibility if needed, so things won't break between merging 2 and 3

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To test:

• Start se-2-challenges from verify-testnets branch Challenge 0: update readme for support OP sepolia #214 . Get your own API key from block explorers or from SRE chat. Deploy to one of the new testnets and verify it. Save link to your contract from block explorer (etherscan etc)
• Run SpeedRunEthereum locally from more-testnets-support branch More testnests support BuidlGuidl/SpeedRunEthereum#209 . My backend .env file contained only AUTOGRADING_SERVER=http://localhost:54727
• Run auto-grader locally from more-testnets-support branch More testnets support austintgriffith/speedrun-grader#10 . Don't forget to add API keys to .env. Run node install to update versions of your challenges
• open your local version of SpeedRunEthereum, submit challenge 0 with your saved link. If everything is ok challenge should be submitted in some seconds

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For now, I created PRs just for discuss, check how it works with challenge 0 and review the code

cc @technophile-04 @Pabl0cks @carletex @damianmarti

[damianmarti]

Maybe only adding support for Base Sepolia is enough and we should change the challenge texts to use Base Sepolia instead of Sepolia.

[technophile-04]

Base Sepolia is enough and we should change the challenge texts to use Base Sepolia instead of Sepolia.

Yup I think one testnet makes more sense!

and base sepolia looks goods to me and we can point people to this page to get sepolia funds: https://docs.base.org/docs/tools/network-faucets/

[rin-st]

added optimism sepolia info to challenge 0 draft readme. Planning to move it to base-challenge-template branch