Update `skaffold` in `cloudbuild.yaml`

[NimJay]

Describe the bug

• Our skaffold.yaml uses skaffold "Modules" — added in https://github.com/GoogleCloudPlatform/microservices-demo/pull/609.
• But the our cloudbuild.yaml file in the root directory uses skaffold v0.20.0 which doesn't support skaffold "Modules". https://github.com/GoogleCloudPlatform/microservices-demo/blob/8cd3ae52c93b2c5be5808c47bbfba1f8002ea13e/cloudbuild.yaml#L28
• We need to:
  • [ ] Update the version of skaffold being used to at least 1.27 (ideally, the latest) in the above cloudbuild.yaml file (in a new branch).
  • [ ] Test that updated cloudbuild.yaml file by creating a Google Cloud Build Trigger targeting the new branch.
  • [ ] Merge changes into main.
• This issue was discovered in #752.

To Reproduce

• We would have to create a Google Cloud Build Trigger pointing to the cloudbuild.yaml file in main.

Logs

• I have not tested this breakage manually, but I assume we should see a message similar to this in the Google Cloud Build Trigger's logs:

WARN[0000] Your Skaffold version might be too old. Download the latest version (1.28.1) from:
  https://github.com/GoogleContainerTools/skaffold/releases/tag/v1.28.1
parsing skaffold config: error parsing skaffold configuration file: unknown skaffold config API version "skaffold/v2beta18". Set the config 'apiVersion' to a known value. Check https://skaffold.dev/docs/references/yaml/ for the list of valid API versions. Otherwise, check that your skaffold version is up-to-date.

Screenshots

N/A

Environment

• Google Cloud Build

Additional context

N/A

Exposure

• This has been broken for a while now (skaffold modules was added in Oct 2021).
• We don't have data on how many people are relying on our cloudbuild.yaml file (i.e., for learning/demo purposes) — I assume it's minimal.

[mathieu-benoit]

Fixed by https://github.com/GoogleCloudPlatform/microservices-demo/pull/885 with explanation there.