Remove the slf4j-api version define

pom.xml

@@ -147,11 +147,6 @@
 				<version>${apollo-java.version}</version>
 			</dependency>
 			<!--third party -->
-			<dependency>
-				<groupId>org.slf4j</groupId>
-				<artifactId>slf4j-api</artifactId>
-				<version>1.7.21</version>
-			</dependency>
 			<dependency>
 				<groupId>com.google.guava</groupId>
 				<artifactId>guava</artifactId>