Ensure AWS SDK dependencies always have the same version

Pin all dependencies from @aws-sdk so that they are always identical.

1. Add a pinned version group

• Match all dependencies whose name starts with @aws-sdk/.
• Mark the version as being pinned to 3.272.0 in this case.
• Add a label to document the decision/expectation.

.syncpackrc

{
  "versionGroups": [
    {
      "dependencies": ["@aws-sdk/**"],
      "pinVersion": "3.272.0",
      "label": "AWS SDK Dependencies should all have the same version"
    }
  ]
}

2. Look for mismatches

Any @aws-sdk packages which do not have the expected version can then be found:

syncpack list-mismatches

And fixed:

syncpack fix-mismatches