Version Updates

Update to latest kubernetes versions and patches.

• v1.19: 1.19.0-alpha.0 -> 1.19.0-beta.0
• v1.18: 1.18.0-rc.1 -> 1.18.3
• v1.17: 1.17.4 -> 1.17.6
• v1.16: 1.16.8 -> 1.16.10
• v1.15: 1.15.11 -> 1.15.12
• pre: 1.19.0-alpha.0 -> 1.19.0-beta.0
• latest: 1.17.4 -> 1.18.3