ci: deployment YAML isn't checked in pull requests

[MichaelAkvo]

Describe the bug

During pull requests, the generated deployment.yaml isn't verified. This can provide a false sense of security / validity. It actually did happen that after the CI for

To Reproduce

Steps to reproduce the behavior:

1. Commit a faulty deployment.template.yaml
2. Create PR
3. Merge into master
4. Open CI page

Expected behavior

When a faulty kubernetes asset is committed, the CI should

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context

Example PR https://github.com/akvo/unep-gpml/pull/1519/files#diff-cc2581b4f520db1cff6c8dfa3fe88773615328acc839926d33f24ffe1eb533b7R167 - the valueFrom is incorrectly indented

Example: CI https://akvo.semaphoreci.com/workflows/4686cfe8-87dc-4716-acc1-d781d11de79d?pipeline_id=c5f49720-cffc-4bc5-b281-6bac8c1ac56e

a kubectl apply --dry-run=client deployment.yaml should help