Add JBang tests and renovate support

[koppor]

We have four JBang scripts: https://github.com/JabRef/jabref/tree/main/.jbang - they specify dependencies inside the files and do not re-use the depdencies in build.gradle.kts.

I think, with Forking Renovate GitHub App and rough JBang tests, we could have automatic updates, similar to dependabot.

Alternative: Write a script updating the version numbers in the JBang scripts //DEP statements based on the information in build.gradle.kts files. Would be another JBang script :p. Maybe 50 lines, but IDK if its worth.

Mandatory checks

• I own the copyright of the code submitted and I license it under the MIT license
• [/] Change in CHANGELOG.md described in a way that is understandable for the average user (if change is visible to the user)
• [/] Tests created for changes (if applicable)
• [/] Manually tested changed features in running JabRef (always required)
• [/] Screenshots added in PR description (if change is visible to the user)
• [/] Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• [/] Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.

[trag-bot]

@trag-bot didn't find any issues in the code! ✅✨