chore: [OpenAPI] Fix broken test (#761)

Co-authored-by: Alexander Dümont <alexander_duemont@web.de>

Author: newtork

datamodel/openapi/openapi-generator-maven-plugin/src/test/java/com/sap/cloud/sdk/datamodel/openapi/generator/DataModelGeneratorMojoUnitTest.java

@@ -8,8 +8,7 @@
 
 import org.apache.maven.plugin.MojoExecutionException;
 import org.apache.maven.plugin.testing.MojoRule;
-// import org.junit.jupiter.api.Test;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 import org.junit.runner.Description;
 import org.junit.runners.model.Statement;