Fix output bound calculations

[bammari]

This PR is to ensure that the bounds on unscaled output vars are calculated from unscaled input bounds. Likewise, it ensures that bounds on scaled output vars are calculated from scaled input bounds

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[codecov]

Codecov Report

Attention: Patch coverage is 92.59259% with 2 lines in your changes missing coverage. Please review.

Project coverage is 90.31%. Comparing base (f85e4e1) to head (f492693).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/omlt/linear_tree/lt_formulation.py	88.88%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #168      +/-   ##
==========================================
- Coverage   90.31%   90.31%   -0.01%     
==========================================
  Files          32       32              
  Lines        2014     2034      +20     
  Branches      316      319       +3     
==========================================
+ Hits         1819     1837      +18     
- Misses        123      124       +1     
- Partials       72       73       +1     

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[bammari]

@jalving This PR is to make sure bounds on output vars are calculated correctly.