feat: migrate to sepolia

[zixiang2018]

What this PR does

• migrate from Goerli to Sepolia testnet
• refactor "goerli" text to "sepolia"
• update test cases in utils.test.ts to check that provider does not have api key, because we are using a workaround to directly call the Alchemy URL (i.e. we use JsonRpcProvider for Sepolia Alchemy Provider case).
  • This testcase will fail once we bump ethers to v6 and use the sepolia-supported AlchemyProvider, which consist of apiKey property.
  • Hence, I added a TODO tag so that we will remember to revert the change in the future bump
  • modified the resolver config for this testcase because Sepolia is not supported in our current version of ethr-did-resolver (we are using the pre-ethers v6 version and v6 has support for Sepolia but is a breaking change)

[github-actions[bot]]

:tada: This PR is included in version 9.1.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: