Bump asciidoctorj-pdf from 2.3.7 to 2.3.9

Bumps [asciidoctorj-pdf](https://github.com/asciidoctor/asciidoctorj-pdf) from 2.3.7 to 2.3.9.
- [Release notes](https://github.com/asciidoctor/asciidoctorj-pdf/releases)
- [Changelog](https://github.com/asciidoctor/asciidoctorj-pdf/blob/main/CHANGELOG.adoc)
- [Commits](https://github.com/asciidoctor/asciidoctorj-pdf/commits/v2.3.9)

---
updated-dependencies:
- dependency-name: org.asciidoctor:asciidoctorj-pdf
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pom.xml

@@ -87,7 +87,7 @@
     <build-helper-maven-plugin.version>3.4.0</build-helper-maven-plugin.version>
     <asciidoctor.maven.plugin.version>2.2.4</asciidoctor.maven.plugin.version>
     <asciidoctorj.version>2.5.10</asciidoctorj.version>
-    <asciidoctorj.pdf.version>2.3.7</asciidoctorj.pdf.version>
+    <asciidoctorj.pdf.version>2.3.9</asciidoctorj.pdf.version>
     <asciidoctorj.diagram.version>2.2.9</asciidoctorj.diagram.version>
     <buildnumber.plugin.version>1.4</buildnumber.plugin.version>
     <jmh.version>1.36</jmh.version>