data/defaults: Fix typo in LoadNixguix task name

And darn, i missed it previously...

Related to !208 (closed)

And i saw it once deployed, because why not.

Test Plan

octocatalog

bin/octocatalog-diff --octocatalog-diff-args --no-truncate-details --to staging worker0.internal.staging.swh.network
Found host worker0.internal.staging.swh.network
WARN     -> Environment "add-validation-server-side" contained non-word characters, correcting name to add_validation_server_side
Cloning into '/tmp/swh-ocd.WaYr4IJj/environments/production/data/private'...
done.
Cloning into '/tmp/swh-ocd.WaYr4IJj/environments/staging/data/private'...
done.
*** Running octocatalog-diff on host worker0.internal.staging.swh.network
I, [2020-03-27T08:21:49.022613 #10666]  INFO -- : Catalogs compiled for worker0.internal.staging.swh.network
I, [2020-03-27T08:21:50.054930 #10666]  INFO -- : Diffs computed for worker0.internal.staging.swh.network
diff origin/production/worker0.internal.staging.swh.network current/worker0.internal.staging.swh.network
*******************************************
  File[/etc/softwareheritage/loader_nixguix.yml] =>
   parameters =>
     content =>
      @@ -19,4 +19,4 @@
         task_broker: amqp://swhconsumer:swh::deploy::worker::task_broker::password@scheduler0.internal.staging.swh.network:5672/%2f
         task_queues:
      -  - swh.loader.package.nixguix.tasks.LoadNixGuix
      +  - swh.loader.package.nixguix.tasks.LoadNixguix
      _
*******************************************
*** End octocatalog-diff on worker0.internal.staging.swh.network

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Migrated from D2900 (view on Phabricator)