Upgrade asciidoctorj-diagram to 2.2.4

[robertpanzer]

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Please take a bit of time giving some details about your pull request:

Kind of change

• [ ] Bug fix
• [x] New non-breaking feature
• [ ] New breaking feature
• [ ] Documentation update
• [ ] Build improvement

Description

What is the goal of this pull request?

Upgrade asciidoctorj-diagram to the latest and greatest, 2.2.4.