Add CI support for Java 20

[otaviojava]

As discussed in today's meeting, Mar 29, we need to support the latest LST, Java 17, and be ready for the next LST version, Java 21.

This issue will create a GitHub Action, CI, to run the source code against Java 20; this won't impact the code behavior. It is an excellent issue to the first contribution.

To-Do:

• [ ] Create a GitHub Action that runs the Jakarta NoSQL source code against Java 20
• [ ] Test the Action and ensure it correctly detects any compatibility issues
• [x] Update the README to document the new CI support for Java 20
• [x] Reproduce the something on communication and extension repositories

[viniciusbrg]

Hello @otaviojava Can I work on this issue?

[otaviojava]

Sure @viniciusbrg

[viniciusbrg]

@otaviojava just opened the PR's in the extensions and databases repo

[otaviojava]

Thank you, @viniciusbrg both merged.