ci: Use aws-actions/configure-aws-credentials@v2

This commit updates the CI workflows to use the AWS
configure-aws-credentials action v2, which is based on node.js 16 and
@actions/core 1.10.0, in preparation for the upcoming removal of the
deprecated GitHub features.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
(cherry picked from commit 9cf94c36)