Follow-up to #13632

Our gradle update workflow (https://github.com/JabRef/jabref/blob/main/.github/workflows/update-gradle-wrapper.yml) cannot update devcontainer gradle version.

Therefore, we need a manual check.

Other options:

• Create an issue in our repository as soon as gradle is updated
• Try with regex magic to update the gradle version in devcontainer.json after a gradle update. (can be a good AI task)

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.