Bump atrium-fluent-en_GB from 0.11.0 to 0.13.0 in /samples/maven

Bumps [atrium-fluent-en_GB](https://github.com/robstoll/atrium) from 0.11.0 to 0.13.0.
- [Release notes](https://github.com/robstoll/atrium/releases)
- [Commits](robstoll/atrium@v0.11.0...v0.13.0)

Signed-off-by: dependabot[bot] <support@github.com>

samples/maven/pom.xml

@@ -11,7 +11,7 @@
 
     <properties>
         <!-- @formatter:off -->
-        <atrium.version>0.11.0</atrium.version>
+        <atrium.version>0.13.0</atrium.version>
         <java.charset>UTF-8</java.charset>
         <java.version>11</java.version>
         <junit.version>5.6.1</junit.version>