fix: upgrade com.thoughtworks.xstream:xstream from 1.4.5 to 1.4.21

Snyk has created this PR to upgrade com.thoughtworks.xstream:xstream from 1.4.5 to 1.4.21.

See this package in maven:
com.thoughtworks.xstream:xstream

See this project in Snyk:
https://app.snyk.io/org/chkp-roniz/project/4a889dff-1acd-46d2-a0bd-d60848588afc?utm_source=github&utm_medium=referral&page=upgrade-pr

Author: snyk-bot

pom.xml

@@ -101,7 +101,7 @@
     <webwolf.context>/</webwolf.context>
     <wiremock.version>3.9.2</wiremock.version>
     <xml-resolver.version>1.2</xml-resolver.version>
-    <xstream.version>1.4.5</xstream.version>
+    <xstream.version>1.4.21</xstream.version>
     <!-- do not update necessary for lesson -->
     <zxcvbn.version>1.9.0</zxcvbn.version>
   </properties>
@@ -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>