Add Ruby 3 support

Adds Ruby 3 support while maintaining 2 support. This is necessarily because Ruby 3 changed how many elements Hash#each yields to lambdas.

Change to aws-sdk-core v3

Swaps out aws-sdk v2 for aws-sdk-core v3 + aws-sdk-secretsmanager v1 in combination.

This should allow the use of EKS ServiceAccount mappings, and OIDC-Federated IAM roles in general.

Update aws-sdk dependency

Updates aws-sdk to enable use of ServiceAccounts in EKS
https://docs.aws.amazon.com/eks/latest/userguide/iam-roles-for-service-accounts-minimum-sdk.html

v0.1.1 Update Rubocop Version

PRs Included:

• Update Rubocop Version