Updated weights loading for DDRNet

[klemen1999]

• Updated path for light and heavy predefined segmentation model weights
• Improved how we load DDRNet head weights, previous ones weren't actually taken into account because of wrong values in the state dict

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.01%. Comparing base (631b905) to head (07e9c2c).
Report is 26 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #148      +/-   ##
==========================================
- Coverage   96.31%   95.01%   -1.31%     
==========================================
  Files         147      170      +23     
  Lines        6304     7523    +1219     
==========================================
+ Hits         6072     7148    +1076     
- Misses        232      375     +143     

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[kozlov721]

LGTM