Add missing SL4J dependency

pom.xml

@@ -162,6 +162,13 @@
 			<artifactId>log4j</artifactId>
 			<version>1.2.16</version>
 		</dependency>
+		<!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-api -->
+		<dependency>
+		    <groupId>org.slf4j</groupId>
+		    <artifactId>slf4j-api</artifactId>
+		    <version>1.7.25</version>
+		</dependency>
+		
 
 		<!-- Parsing, Bytecode, ... -->
 		<!-- Unused <dependency> <groupId>antlr</groupId> <artifactId>antlr</artifactId>