Reactivate bugged Fellow tasklist emails

templates/email/fellows/email_fellow_tasklist.json

 {
     "subject": "SciPost: current assignments, pending tasks",
-    "to_address": "fellow.user.email",
+    "to_address": "user.email",
     "bcc_to": "edadmin@scipost.org",
     "from_address_name": "SciPost EdAdmin",
     "from_address": "edadmin@scipost.org",