make gitlab-k8s-agent-update does not update to the latest commit

Overview

make gitlab-k8s-agent-update fetches the latest commits from remote but then it tries to check out master, which is already the current branch so it does not get updates from remote merged into it.

Fetching origin
Already on 'master'
Your branch is behind 'origin/master' by 35 commits, and can be fast-forwarded.
  (use "git pull" to update your local branch)

Proposal (optional)

🤷

Kubernetes Agent is currently under active development and behind a feature flag in both the main application and GDK. Normally a commit sha would be specified as a version, not master so this is not a problem for other components, but for the agent we'd like to always get the latest changes from remote on update.

One option would be to hardcode a check for master and do a git pull instead of fetch+checkout. Any better ideas?