Knative version bump 0.5 -> 0.6

What does this MR do?

Update the Knative components to use Knative-0.6

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

Verification done by hand using GKE and a sample serverless.yml/.gitlab-ci.yml files and the tm cli program. The deploy service from image does work as expected, however there is an incompatability with the tm CLI and will require at least v0.0.11 or newer.

This is a backend only change so browser testing is not required.

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers