Bump agent to 3.10.3
Bump agent to 3.10.3

Signed-off-by: Jeremiah Snapp <a9df78b4b5c00745f26b0821b2cc57336a474862@chef.io>

holmesjr/elastic-ci-stack-for-aws,holmesjr/elastic-ci-stack-for-aws,buildkite/elastic-ci-stack-for-aws