RFR: 8296153: Bump minimum boot jdk to JDK 20

Fri Apr 21 20:54:53 UTC 2023

On Thu, 20 Apr 2023 19:15:00 GMT, Mikael Vidstedt <mikael at openjdk.org> wrote:

> With the JDK 20 GA out it's time to bump the minimum boot JDK version for mainline/JDK 21.
> 
> Testing: tier1-5, GHA (the Windows build successfully downloads the JDK but then fails for unrelated reasons, and one seemingly unrelated Vector API test failure in tier 3)

Thank you for the reviews!

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PR Comment: https://git.openjdk.org/jdk/pull/13565#issuecomment-1518322647