fix(export): set a random UUID key before forcing not null

lib/tasks/deployment/20210402000000_null_export_keys_to_uuid.rake

@@ -0,0 +1,13 @@
+namespace :after_party do
+  desc 'Deployment task: null_exports_key_to_uuid'
+  task null_exports_key_to_uuid: :environment do
+    puts "Running deploy task 'null_exports_key_to_uuid'"
+
+    Export.where(key: nil).update_all(key: SecureRandom.uuid)
+
+    # Update task as completed.  If you remove the line below, the task will
+    # run with every deploy (or every time you call after_party:run).
+    AfterParty::TaskRecord
+      .create version: AfterParty::TaskRecorder.new(__FILE__).timestamp
+  end
+end