Peer deps on @aws-cdk/*-alpha packages

[moltar]

It looks like the peerDependencies always matches the version of the published package. Not sure if this is intentional.

Typically, peerDependencies should stay pinned to a concrete version, and should only change if there was, in fact, an incompatible change.

Also a change in peerDependencies, even a patch, is considered to be a breaking change according to SemVer, and would then require a major bump on the package that declares the peer dependency.

This behaviour is undesirable, as it is impossible to use strict peer deps setting in the package manager config, which is the correct way to define deps.

This is in the context of building reusable constructs. My reusable construct defines a peer as 2.100.0, but these alpha packages define a peer as "aws-cdk-lib": "^2.123.0", and then pnpm` fails with:

└─┬ @aws-cdk/integ-tests-alpha 2.123.0-alpha.0
  └── ✕ unmet peer aws-cdk-lib@^2.123.0: found 2.100.0