Add CI into the JNoSQL Extensions project to support for Java 21

[dearrudam]

Last September 19th, the latest Java LTS, Java 21 was released and JNoSQL Extensions project should be able to run against Java 21.

This issue will create a GitHub Action, CI, to run the source code against Java 21; this won't impact the code behavior. It is an excellent issue to the first contribution.

To-Do:

• [x] Create a GitHub Action that runs the Jakarta NoSQL source code against Java 21
• [x] Test the Action and ensure it correctly detects any compatibility issues
• [x] Update the README to document the new CI support for Java 21

[vimalJD]

Is this project is ongoing? Let me know further (DOCS) to contribute on it as "good first issue".

[dearrudam]

Yes, @vimalJD! The JNoSQL Extensions project is active!

The Eclipse JNoSQL Mapping Extension API is a collection of implementations/specializations from the Jakarta NoSQL specification that defines specific behavior in various NoSQL databases.

To learn more about how to contribute to this project, take a look at the Contributing section in the README file, please. 👍