fix: variable length tuples of compound types

[PrettyWood]

Change Summary

I changed recently the code related to tuple to be more explicit and support () (empty tuple) but missed the case of variable length tuples of compound types

Related issue number

closes #2416

Checklist

• Unit tests for the changes exist
• Tests pass on CI and coverage remains at 100%
• Documentation reflects the changes where applicable
• changes/<pull request or issue id>-<github username>.md file added describing change
  (see changes/README.md for details)

[codecov]

Codecov Report

Merging #2421 (3bc6777) into master (a8d50ae) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master     #2421   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           25        25           
  Lines         5080      5081    +1     
  Branches      1041      1041           
=========================================
+ Hits          5080      5081    +1     

Impacted Files	Coverage Δ
pydantic/fields.py	100.00% <100.00%> (ø)

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[samuelcolvin]

LGTM, @tlambert03 are you happy with this fix?

[tlambert03]

works for me! thanks for the quick fix