chore: support goerli

[zixiang2018]

Context: Ropsten is deprecated, causing fixtures on ropsten to be deprecated as well. Will have to migrate to Goerli to support this deprecation changes.

What this PR does:

• bump @govtechsg/opencerts-verify to 3.1.1
• bump @govtechsg/open-attestation version to 6.5.1
• bump @govtechsg/decentralized-renderer-react-components to 3.8.0
• bump testcafe version to 2.0.1
• replace ropsten demo cert with goerli demo cert (the "click me for demo")
• add goerli doc store into the registry.json
• updated fixtures to use goerli document store
• updated fixtures with old schema to use OA v2 (https://schema.openattestation.com/2.0/schema.json)
• fixes #685