Update CODEOWNERS with Jason Krause/ Blake Hearn as codeowners for anchore....

Summary

Updated file with nick nellis as istio codeowner, jason krause and blake hearn as codeowners for anchore; removed andre

/cc @someoneelse

• ISTIO Control Plane
• GateKeeper
• Twistlock
• Anchore
• KeyCloak
• Authservice
• ArgoCD