Bump version to 3.3.1-SNAPSHOT

build.gradle

@@ -6,7 +6,7 @@ apply plugin: 'signing'
 
 allprojects {
   project.group = 'de.hhu.stups'
-  project.version = '3.3.0'
+  project.version = '3.3.1-SNAPSHOT'
   project.ext.isSnapshot = project.version.endsWith("-SNAPSHOT")
 
   ext."signing.secretKeyRingFile" = rootProject.file("secring.gpg").absolutePath