Fix inadvertent removal of __all__

[stscirij]

No JP ticket or issue for this fix

This PR puts back the _all statement that got inadvertently removed in a previous PR

Tasks

• If you have a specific reviewer in mind, tag them.
• add a build milestone, i.e. Build 12.0 (use the latest build if not sure)
• Does this PR change user-facing code / API? (if not, label with no-changelog-entry-needed)
  • write news fragment(s) in changes/: echo "changed something" > changes/<PR#>.<changetype>.rst (see changelog readme for instructions)
  • update or add relevant tests
  • update relevant docstrings and / or docs/ page
  • start a regression test and include a link to the running job (click here for instructions)
    • Do truth files need to be updated ("okified")?
      • after the reviewer has approved these changes, run okify_regtests to update the truth files
• if a JIRA ticket exists, make sure it is resolved properly

[melanieclarke]

Looks good, thanks Robert! No need to run regression tests for this.

[pllim]

Just a small comment. Thanks!

[pllim]

If user won't notice anything, not sure if this actually needs a change log. I'll leave that up to you. If you want to keep it, here is a suggestion.

Suggested change

	Restore __all__ definition that was removed in an earlier PR
	Restore ``__all__`` definition that was removed in an earlier PR.

[stscirij]

Thanks, I kept it with your suggestion!

[tapastro]

@meeseeksdev backport to release/1.18.x

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.69%. Comparing base (86af1f2) to head (31efdf8).
Report is 742 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9338   +/-   ##
=======================================
  Coverage   74.69%   74.69%           
=======================================
  Files         369      368    -1     
  Lines       37117    37107   -10     
=======================================
- Hits        27723    27718    -5     
+ Misses       9394     9389    -5     

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[pllim]

Just for accurate bookkeeping, does that mean milestone for this PR and its backport is really 11.3, not 12.0?

[melanieclarke]

Just for accurate bookkeeping, does that mean milestone for this PR and its backport is really 11.3, not 12.0?

Yes, it should be 11.3. I'll update it.