Update slf4j-api to 1.7.7

Change-Id: I15bd1aca606400c5f19016be6283e8bafa17b361
diff --git a/pom.xml b/pom.xml
index b5309a3..701225d 100644
--- a/pom.xml
+++ b/pom.xml
@@ -618,7 +618,7 @@
     <dependency>
       <groupId>org.slf4j</groupId>
       <artifactId>slf4j-api</artifactId>
-      <version>1.7.5</version>
+      <version>1.7.7</version>
     </dependency>
     <dependency>
       <groupId>com.google.guava</groupId>