[deps]: Bump org.commonmark:commonmark from 0.19.0 to 0.21.0 (#2150)

Bumps [org.commonmark:commonmark](https://github.com/commonmark/commonmark-java) from 0.19.0 to 0.21.0.
- [Release notes](https://github.com/commonmark/commonmark-java/releases)
- [Changelog](https://github.com/commonmark/commonmark-java/blob/main/CHANGELOG.md)
- [Commits](commonmark/commonmark-java@commonmark-parent-0.19.0...commonmark-parent-0.21.0)

---
updated-dependencies:
- dependency-name: org.commonmark:commonmark
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

javalin-rendering/pom.xml

@@ -93,7 +93,7 @@
         <dependency>
             <groupId>org.commonmark</groupId>
             <artifactId>commonmark</artifactId>
-            <version>0.19.0</version>
+            <version>0.21.0</version>
             <optional>true</optional>
         </dependency>
         <!-- END OPTIONAL TEMPLATE ENGINES -->