Pin Serverless major version to < 4.x due to license changes

[Callek]

I think this is right.

See one example of the serverless v4 renovate bump in https://github.com/anaconda-distribution/rocket-platform/pull/1250
Or in https://github.com/anaconda/lambdas/pull/607

[Callek]

As we announced at the end of 2023, Serverless Framework CLI will continue to be free for individual developers and small businesses, but will no longer be free for Organizations that have greater than $2M in annual revenue. These Organizations will require a commercial Subscription.

These changes only apply to Serverless Framework V.4 and beyond and not to earlier versions. Serverless Framework V.3 will continue to be maintained via critical security and bug fixes through 2024.