Expand aws-sdk-core version dependency
Expand aws-sdk-core version dependency

By changing the version to `~>2.0` then users can safely upgrade to `2.1`, `2.2`, etc. The `aws-sdk-core` gem follows semver, so minor version bumps should be backwards compatible.
AutoScout24/aws-fluent-plugin-kinesis,atlassian/fluent-plugin-kinesis-aggregation,awslabs/aws-fluent-plugin-kinesis,winebarrel/aws-fluent-plugin-kinesis,atlassian/aws-fluent-plugin-kinesis