Bump log4j.version from 2.23.0 to 2.23.1 (#43)

Bumps `log4j.version` from 2.23.0 to 2.23.1.
Updates `org.apache.logging.log4j:log4j-api` from 2.23.0 to 2.23.1

Updates `org.apache.logging.log4j:log4j-core` from 2.23.0 to 2.23.1

Updates `org.apache.logging.log4j:log4j-slf4j2-impl` from 2.23.0 to
2.23.1

Updates `org.apache.logging.log4j:log4j-layout-template-json` from
2.23.0 to 2.23.1


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pom.xml

@@ -13,7 +13,7 @@
         <maven.compiler.target>1.8</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <fhir.version>7.0.2</fhir.version>
-        <log4j.version>2.23.0</log4j.version>
+        <log4j.version>2.23.1</log4j.version>
         <fasterxml.version>2.16.1</fasterxml.version>
         <sonar.organization>nhsdigital</sonar.organization>
         <sonar.host.url>https://sonarcloud.io</sonar.host.url>