[tahoe-lafs-trac-stream] [Tahoe-LAFS] #3944: GitHub Actions workflow upkeep

[Tahoe-LAFS]

#3944: GitHub Actions workflow upkeep
--------------------------------+---------------------------
 Reporter:  sajith              |          Owner:  sajith
     Type:  task                |         Status:  new
 Priority:  normal              |      Milestone:  undecided
Component:  dev-infrastructure  |        Version:  n/a
 Keywords:                      |  Launchpad Bug:
--------------------------------+---------------------------
 Each run of !GitHub Actions with the current configuration emits many
 warnings about deprecations. Consider this workflow run, for example:

 https://github.com/tahoe-lafs/tahoe-lafs/actions/runs/3533138743

 There are a 100 warnings, mostly duplicates.  The warnings are due to:

  - Node.js 12 actions are deprecated. It seems that actions/checkout at v2,
 actions/setup-python at v2, actions/cache at v2, actions/upload-artifact at v2 all
 use older Node.js. They are all probably due for an upgrade.
  - `set-output` and `save-state` commands are deprecated and will be
 disabled soon.  This is from the pip caching steps; we can simply remove
 that and use the equivalent feature available in newer version of `actions
 /setup-python.

 While we are on this, it probably is a good idea to stick this incantation
 in the workflow file so that the `GITHUB_TOKEN` issued at the beginning of
 the workflow will have a minimum set of permissions:

 {{{
 permissions:
   contents: read
 }}}

 Relevant !GitHub docs are [https://docs.github.com/en/actions/security-
 guides/automatic-token-authentication Automatic token authentication] and
 [https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-
 github-actions#permissions Workflow syntax for GitHub Actions:
 permissions].

 I understand that GH Actions do not get a lot of love from Tahoe-LAFS
 team, and some of us would love to throw the thing away entirely. However,
 as long as Tahoe-LAFS uses GH Actions, it is a good idea to do the minimum
 upkeep.

--
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3944>
Tahoe-LAFS <https://Tahoe-LAFS.org>
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