added infura credential environment variables

[praveen-kaia]

Proposed changes

• Added Infura project key, secret environment variables to support the latest caverjs with infura changes

Types of changes

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• [x] Bugfix
• [ ] New feature or Enhancement
• [ ] Others

Checklist

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• [x ] I have read the CONTRIBUTING GUIDELINES doc
• [ ] I have signed the CLA
• [ ] Lint and unit tests pass locally with my changes
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation (if appropriate)
• [ ] Any dependent changes have been merged and published in downstream modules

Further comments

Once caverjs infura changes are merged, the caverjs package version has to be changed in klaytn-dev-sandbox.

[0xxlegolas]

@praveen-klaytn https://github.com/klaytn/klaytn-dev-sandbox/blob/dev/src/components/KIP17.tsx#L103 The url does not work anymore. We might need to change the method to post method https://docs.infura.io/infura/networks/ipfs/http-api-methods/get