Bump org.asciidoctor:asciidoctorj-pdf from 2.3.12 to 2.3.13 (#767)

Bumps [org.asciidoctor:asciidoctorj-pdf](https://github.com/asciidoctor/asciidoctorj-pdf) from 2.3.12 to 2.3.13.
- [Release notes](https://github.com/asciidoctor/asciidoctorj-pdf/releases)
- [Changelog](https://github.com/asciidoctor/asciidoctorj-pdf/blob/main/CHANGELOG.adoc)
- [Commits](asciidoctor/asciidoctorj-pdf@v2.3.12...v2.3.13)

---
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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

spec/pom.xml

@@ -25,7 +25,7 @@
 	<properties>
 		<asciidoctor-maven.version>3.0.0</asciidoctor-maven.version>
 		<asciidoctorj.version>2.5.11</asciidoctorj.version>
-		<asciidoctorj-pdf.version>2.3.12</asciidoctorj-pdf.version>
+		<asciidoctorj-pdf.version>2.3.13</asciidoctorj-pdf.version>
 		<!-- asl2 for non-final releases, or final for EFSL -->
 		<license-file>asl2</license-file>
 		<!-- Draft for non-final releases, or Final for spec release -->