Bump cert-manager to v1.8.0

[AcidLeroy]

What this PR does / why we need it

Need the latest version of cert-manager to support newer versions of Kubernetes. See compatibility document for reference.

Signed-off-by: Cody W. Eilar [email protected]

Which issue(s) this PR fixes

VKAL-14829 Fixes #

Describe testing done for PR

Only performed make test

Release note

Bump cert-manager to v1.8.0.