Add serverless as dev dependency and update to version 3

[jyenduri-uptycs]

Issue Link: #106

Uploaded file must be a non-empty zip

What does it do?

Today, with current master branch, when we follow the installation instructions we get this error

Serverless Error ---------------------------------------

An error occurred: AutoRemediateConfigDash001LambdaFunction - Resource handler returned message: "Uploaded file must be a non-empty zip (Service: Lambda, Status Code: 400, Request ID: ---, Extended Request ID: null)" (RequestToken: ---, HandlerErrorCode: InvalidRequest).

This PR,

1. Will update serverless to version : 3
2. Also removed reservedConcurrency for AutoRemediateOrchestrator lambda function

Checklist

• I will squash: PR title conforms to standard commit message format (feat: XX-1234 ...)
• I will merge without squashing: All commits conforms to standard commit message format (feat: XX-1234 ...)
• README update

---

Notes to reviewers

(eg. Majority of LOC changes were prettier. Specific file to look at is package.json)

1. Look at the version of serverless
2. Also we have to update the image in the readme, we have to update about SQS and KMS usage.

[jyenduri-uptycs]

Please take a look @binli0114 / @edmundcong / @mikerahmati / @cpuccino

[PatrickQuintal]

Hey @jyenduri-uptycs , Thanks for your contribution. Coincidentally, you've tagged a few individuals that no longer work with Conformity so we didn't catch this PR!

Coincidentally we were just talking about upgrading this repo to serverless 3, which we've got a PR done here: #110 if you want to have a look.

I am interested though in your second change, any particular reason you removed reservedConcurrency for AutoRemediateOrchestrator?

[binli0114]

Hey @jyenduri-uptycs , Thanks for your contribution. Coincidentally, you've tagged a few individuals that no longer work with Conformity so we didn't catch this PR!

Coincidentally we were just talking about upgrading this repo to serverless 3, which we've got a PR done here: #110 if you want to have a look.

I am interested though in your second change, any particular reason you removed reservedConcurrency for AutoRemediateOrchestrator?

@PatrickQuintal
I have the same question regarding the change on the reservedConcurrency.