Add Qiskit4Java to list.

[github-actions]

Add Qiskit4Java to list.

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Closes #1009

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
2 out of 3 committers have signed the CLA.

✅ gnietof
✅ 1ucian0
❌ GitHub

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GitHub seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

I assume the thump up reaction as "commit these changes please"