chore: remove duplicated slf4j-simple dependency in vaadin-tabs-flow module (#8151)

Author: DiegoCardoso

vaadin-tabs-flow-parent/vaadin-tabs-flow/pom.xml

@@ -50,11 +50,6 @@
             <artifactId>slf4j-simple</artifactId>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.slf4j</groupId>
-            <artifactId>slf4j-simple</artifactId>
-            <scope>test</scope>
-        </dependency>
     </dependencies>
     <build>
         <plugins>