Deploy new sourceforge lister task

Related to T3310

Test Plan

octo-diff

$ bin/octocatalog-diff --octocatalog-diff-args --no-truncate-details --to staging worker0.internal.staging.swh.network
...
I, [2021-05-07T15:31:39.545393 #26821]  INFO -- : Catalogs compiled for worker0.internal.staging.swh.network
I, [2021-05-07T15:31:40.672512 #26821]  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/lister.yml] =>
   parameters =>
     content =>
      @@ -32,4 +32,5 @@
         - swh.lister.phabricator.tasks.FullPhabricatorLister
         - swh.lister.pypi.tasks.PyPIListerTask
      +  - swh.lister.sourceforge.tasks.FullSourceForgeLister
       credentials:
         github:
*******************************************
*** End octocatalog-diff on worker0.internal.staging.swh.network

---

Migrated from D5713 (view on Phabricator)