Bump atrium-fluent-en_GB from 0.11.0 to 0.13.0 in /samples/jvm/junit5

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](v0.11.0...v0.13.0)

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

samples/jvm/junit5/build.gradle

@@ -5,7 +5,7 @@ import org.gradle.api.tasks.testing.logging.TestExceptionFormat
 
 buildscript {
     ext {
-        atrium_version = '0.11.0'
+        atrium_version = '0.13.0'
         junit_version = '5.3.1'
     }
 }