[VOTE] Deprecate Java 8 Support

[Xavier Bai]

I propose that we drop support for Java 8 and upgrade our minimum required
JDK version to Java 11 when the 0.9.0 release comes out.

The VOTE will pass after 3 binding approvals.

[ ] +1 approve
[ ] +0 no opinion
[ ] -1 disapprove with the reason