update publication scripts

tgbotapi.extensions.behaviour_builder/publish.gradle

@@ -1,4 +1,5 @@
 apply plugin: 'maven-publish'
+apply plugin: 'signing'
 
 task javadocsJar(type: Jar) {
     classifier = 'javadoc'
@@ -66,4 +67,9 @@ publishing {
         }
         
     }
-}
+}
+
+signing {
+    useGpgCmd()
+    publishing.publications.forEach { sign it }
+}