chore(examples): Lock servlet dep on slf4j

Author: kattrali

examples/servlet/build.gradle

@@ -17,7 +17,7 @@ repositories {
 }
 
 dependencies {
-    runtime 'org.slf4j:slf4j-simple:1.+'
+    runtime 'org.slf4j:slf4j-simple:1.7.25'
     compile rootProject
 }