Update GitHub thumbprints for OIDC in CI (#2813)

CI uses an `OpenIdConnectProvider` to grant access to certain operations
in the CI AWS account to the GitHub Actions runners. This provider
checks the certificate thumbprints to validate the authenticity of
connect requests. GitHub recently [added a new
thumbprint](https://github.blog/changelog/2023-06-27-github-actions-update-on-oidc-integration-with-aws/),
which was causing CI and the PR bot to intermittently fail since the
OIDC provider wasn't aware of it. This PR corrects the thumbprints to
reestablish consistency in CI.

----

_By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice._