Verify our certificates are compatible with OCP 4.6/golang 1.15

OCP 4.6 is compiled with golang 1.15 which introduced a backwards-incompatible change regarding certificate validation: https://golang.google.cn/doc/go1.15#commonname

According to some folks in serverless this is breaking our webhooks in 1.1 (and likely also 1.0) control planes and the operator (thanks bbrownin@redhat.com and maschmid@redhat.com for pointing out this problem to us).

OCP Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1883690