remove unused logback dependency (#88)

Author: elharo

pom.xml

@@ -188,12 +188,6 @@ under the License.
       <artifactId>junit-jupiter</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>ch.qos.logback</groupId>
-      <artifactId>logback-classic</artifactId>
-      <version>1.3.11</version>
-      <scope>test</scope>
-    </dependency>
     <dependency>
       <groupId>org.slf4j</groupId>
       <artifactId>log4j-over-slf4j</artifactId>