fix unmarshal errors not found for known k8s schema

[fedeztk]

Description

Fixes #523 (known schema not raising errors when incompatible with k8s resource definitions)

Type of change

• Bug fix 🐛
• New feature ✨
• This change requires a documentation update 📖
• Breaking changes ⚠️

How Has This Been Tested?

Tested using the example provided in #523. Prior to this change there was no error; now, known resources (e.g. Deployments) raise an error when the unmarshaling goes wrong (like unquoted labels) and clearly shows that there is a misconfiguration in the manifest.

Checklist:

• I have 🎩 my changes (A 🎩 specifically includes pulling down changes, setting them up, and manually testing the changed features and potential side effects to make sure nothing is broken)
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• The test coverage did not decrease
• I have signed the appropriate Contributor License Agreement