Certificate Objects result in an 'update' when no changes were made

[deirdre-anderson]

If you configure a Certificate entity in Kong with a cert and key. A 'deck dump' and a subsequent 'deck sync' will result in the message that an update was made despite no changes being made between the dump and sync.

Reproduce :

1. Configure a 'Certificate Object' cert and key in Kong (EE in this scnario)
2. 'deck dump -o debug.yaml' --headers 'kong-admin-token:'
3. 'deck sync -s debug.yaml' --headers 'kong-admin-token:'
4. The output of the sync/diff is the below - when in fact no changes where made between the 'dump' and subsequent 'sync':
   updating certificate b734b681-359a-4242-bd0b-febe6f2464f0 {
   ...
   Summary:
   Created: 0
   Updated: 1
   Deleted: 0