Bump Container Registry to v3.68.0

What does this MR do?

3.68.0 (2023-03-01)

Features

• datastore: add index to speed up lookups of manifests by tag (069a705)

Related issues

Related to https://gitlab.com/gitlab-com/gl-infra/production/-/issues/8407+.

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion

Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Integration tests added to GitLab QA
• The impact any change in container size has should be evaluated