Renovate: Update dependency kubernetes/kubernetes to v1.19.4

Renovate has identified updated artifacts for this project.

ironbank-bot does not currently support updating the greylist file to match the version indicated by Renovate. Not does it support validating pipeline status. Please ensure these are handled manually.

Definition of Done:

• Merge topic branch in dccscr-whitelists into master
• Merge topic branch into development
• Merge development into master

If this update produces new findings, perform the following (use this ticket instead of creating a new one):

• Assign label Container::New Findings
• Submit justifications and start approval process.