ci: Add a test for synchronizing auto-deploy-app chart version

This is motivated by !100 (comment 385932560).

This MR introduces a test script to check if a prospect release version by semantic-release matches the version of the bundled chart. This is helpful not to forget to update the chart version when a developer creates a new release of auto-deploy-image.

Here is an example of test failure https://gitlab.com/gitlab-org/cluster-integration/auto-deploy-image/-/jobs/659103150. It includes a dummy feat: commit so semantic-release will release 1.0.0-beta.2, however, auto-deploy-app chart version is set to 1.0.0 so the job prompts developers to set 1.0.0-beta.2 to the chart. (This message is a bit logically odd because we've already merged !101 (merged))