fix: pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-ORGJRUBY-10074039
- https://snyk.io/vuln/SNYK-JAVA-ORGJRUBY-10557729

Author: snyk-bot

pom.xml

@@ -62,7 +62,7 @@
 
   <properties>
     <!-- Shared properties with plugins and version numbers across submodules-->
-    <asciidoctorj.version>3.0.0</asciidoctorj.version>
+    <asciidoctorj.version>3.0.1</asciidoctorj.version>
     <bootstrap.version>5.3.3</bootstrap.version>
     <cglib.version>3.3.0</cglib.version>
     <!-- do not update necessary for lesson -->
@@ -539,8 +539,8 @@
               <includes>
                 <include>.gitignore</include>
               </includes>
-              <trimTrailingWhitespace></trimTrailingWhitespace>
-              <endWithNewline></endWithNewline>
+              <trimTrailingWhitespace/>
+              <endWithNewline/>
               <indent>
                 <tabs>true</tabs>
                 <spacesPerTab>4</spacesPerTab>
@@ -551,15 +551,15 @@
             <includes>
               <include>**/*.md</include>
             </includes>
-            <flexmark></flexmark>
+            <flexmark/>
           </markdown>
           <java>
             <includes>
               <include>src/main/java/**/*.java</include>
               <include>src/test/java/**/*.java</include>
               <include>src/it/java/**/*.java</include>
             </includes>
-            <removeUnusedImports></removeUnusedImports>
+            <removeUnusedImports/>
             <googleJavaFormat>
               <style>GOOGLE</style>
               <reflowLongStrings>true</reflowLongStrings>