Feature/scheduler fix

[Elson9]

Description

In Kong 3, the /snis endpoint returns a slightly different JSON format for certificates:

Kong2:
"certificate": "example-cert",

Kong3:
"certificate": { "id": "example-cert" },

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Documentation (non-breaking change with enhancements to documentation)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have checked that unit tests pass locally with my changes
• I have updated tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments