create activity for 'user deleted'; Fixes #985

src/model/user/mod.rs

@@ -583,12 +583,12 @@ ASKÖ Ruderverein Donau Linz", self.name),
             .await;
     }
 
-    pub async fn delete(&self, db: &SqlitePool) {
+    pub async fn delete(&self, db: &SqlitePool, deleted_by: &ManageUserUser) {
         sqlx::query!("UPDATE user SET deleted=1 WHERE id=?", self.id)
             .execute(db)
             .await
             .unwrap(); //Okay, because we can only create a User of a valid id
-        ActivityBuilder::new(&format!("User {self} wurde gelöscht."))
+        ActivityBuilder::new(&format!("User {self} wurde von {deleted_by} gelöscht."))
             .relevant_for_user(self)
             .save(db)
             .await;