fix: Lazy loading breaks noop

[adammcdonagh]

Prevent new lazy loading logic to load in unresolved variables from conflicting with the no op functionality where some variables are intentionally not resolved.

[codecov]

Codecov Report

Attention: Patch coverage is 86.66667% with 2 lines in your changes missing coverage. Please review.

Project coverage is 88.77%. Comparing base (f1b00c8) to head (e6ec538).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/opentaskpy/config/loader.py	86.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #96      +/-   ##
==========================================
- Coverage   88.85%   88.77%   -0.08%     
==========================================
  Files          20       20              
  Lines        2396     2397       +1     
==========================================
- Hits         2129     2128       -1     
- Misses        267      269       +2     

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