Update amazon/aws-cli Docker tag to v2.16.8

This MR contains the following updates:

Package	Type	Update	Change
amazon/aws-cli		patch	2.16.7 -> 2.16.8
amazon/aws-cli	ironbank-docker	patch	2.16.7 -> 2.16.8
amazon/aws-cli	stage	patch	2.16.7 -> 2.16.8

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