sfn-dynamodb-cdk: Update aws-cdk-lib

[kakakakakku]

Issue #, if available:
N/A

Description of changes:
Hi😀 Thanks for the useful patterns!

To keep this pattern maintainable, I updated the aws-cdk-lib.

Check

cdk deploy completed successfully and works good.

$ aws stepfunctions start-execution --name "test" --state-machine-arn "arn:aws:states:ap-northeast-1:000000000000:stateMachine:SfnToDDBWorkflowStateMachineF8331466-tFjmMlBVha2G" --input "{\"id\": \"12345\" }"
{
    "executionArn": "arn:aws:states:ap-northeast-1:000000000000:execution:SfnToDDBWorkflowStateMachineF8331466-tFjmMlBVha2G:test",
    "startDate": "2026-07-06T23:08:59.511000+09:00"
}

$ aws dynamodb get-item --table-name SfnDynamodbCdkStack-MyDDBTableName1F0038E0-O9EBX1QFKON3 --key "{\"id\": {\"S\": \"12345\"} }"
{
    "Item": {
        "description": {
            "S": "Hello, my id is 12345."
        },
        "id": {
            "S": "12345"
        }
    }
}

Thank you😀

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[kakakakakku]

[WARNING] aws-cdk-lib.aws_stepfunctions.StateMachineProps#definition is deprecated.
  use definitionBody: DefinitionBody.fromChainable()
  This API will be removed in the next major release.