Update amazon/aws-cli Docker tag to v2.15.0

This MR contains the following updates:

Package	Type	Update	Change
amazon/aws-cli	ironbank-docker	minor	2.14.5 -> 2.15.0
amazon/aws-cli		minor	2.14.5 -> 2.15.0
amazon/aws-cli	stage	minor	2.14.5 -> 2.15.0

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