update javax-servlet-api to 3.1.0

this is a forgotten version upgrade. recent version of Tomcat support 3.1.0

build.gradle

@@ -189,7 +189,7 @@ subprojects {
       dependency 'io.netty:netty-all:4.0.51.Final'
       dependency 'com.sun.mail:javax.mail:1.5.6'
       dependency 'javax.annotation:javax.annotation-api:1.3.1'
-      dependency 'javax.servlet:javax.servlet-api:3.0.1'
+      dependency 'javax.servlet:javax.servlet-api:3.1.0'
       dependency 'javax.xml.bind:jaxb-api:2.3.0'
       dependency 'junit:junit:4.12'
       dependency 'net.jpountz.lz4:lz4:1.3.0'