Bump log4j.version from 2.11.1 to 2.13.3 in /samples/struts2/pet-store (#360)

Bumps `log4j.version` from 2.11.1 to 2.13.3.

Updates `log4j-core` from 2.11.1 to 2.13.3

Updates `log4j-api` from 2.11.1 to 2.13.3

Updates `log4j-slf4j-impl` from 2.11.1 to 2.13.3

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

Author: dependabot[bot]

samples/struts2/pet-store/pom.xml

@@ -29,7 +29,7 @@
         <struts2.version>2.5.22</struts2.version>
         <jackson.version>2.10.3</jackson.version>
         <junit.version>4.12</junit.version>
-        <log4j.version>2.11.1</log4j.version>
+        <log4j.version>2.13.3</log4j.version>
     </properties>
 
     <dependencies>