Add a cronjob to trigger beta releases 3 times a week

This mimics the schedule found in bitrise

Author: Eijebong

.cron.yml

@@ -30,3 +30,16 @@ jobs:
           firefox-ios:
             - {hour: 22, minute: 0}
           default: []
+    - name: beta-releases
+      job:
+        type: decision-task
+        target-tasks-method: beta_releases
+        treeherder-symbol: beta_releases
+      when:
+        by-project:
+          firefox-ios:
+            - {weekday: 'Tuesday', hour: 23, minute: 0}
+            - {weekday: 'Thursday', hour: 23, minute: 0}
+            - {weekday: 'Sunday', hour: 23, minute: 0}
+          default: []
+