Bump org.asciidoctor:asciidoctorj-pdf from 2.3.9 to 2.3.18

Bumps [org.asciidoctor:asciidoctorj-pdf](https://github.com/asciidoctor/asciidoctorj-pdf) from 2.3.9 to 2.3.18.
- [Release notes](https://github.com/asciidoctor/asciidoctorj-pdf/releases)
- [Changelog](https://github.com/asciidoctor/asciidoctorj-pdf/blob/main/CHANGELOG.adoc)
- [Commits](asciidoctor/asciidoctorj-pdf@v2.3.9...v2.3.18)

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

Signed-off-by: dependabot[bot] <[email protected]>

pom.xml

@@ -1275,7 +1275,7 @@
                             <dependency>
                                 <groupId>org.asciidoctor</groupId>
                                 <artifactId>asciidoctorj-pdf</artifactId>
-                                <version>2.3.9</version>
+                                <version>2.3.18</version>
                             </dependency>
                         </dependencies>
                         <executions>