Fix 2 tuple type annotations in TimeSeries

[ajyoon]

Checklist before merging this PR:

• [ ] ~~Mentioned all issues that this PR fixes or addresses.~~ (N/A)
• [x] Summarized the updates of this PR under Summary.
• [ ] Added an entry under Unreleased in the Changelog.

Summary

• TimeSeries.shape was incorrectly annotated tuple[int]; this is changed to tuple[int, int, int].
• The quantiles argument in TimeSeries.quantiles_df was incorrectly annotated tuple[float]; this is changed to tuple[float, ...].

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 95.18%. Comparing base (b71851b) to head (5324c4e). Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2812      +/-   ##
==========================================
- Coverage   95.26%   95.18%   -0.08%     
==========================================
  Files         145      145              
  Lines       15126    15126              
==========================================
- Hits        14410    14398      -12     
- Misses        716      728      +12     

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[ajyoon]

@dennisbader apologies for my delay - looks like you beat me on the quantiles change, so I've merged upstream and removed those changes. This PR is now just the annotation fix on TimeSeries.shape