Adds TStreamerSTLstring support

[tamasgal]

Fixes #377

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.59%. Comparing base (26bec3d) to head (4c52560).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #378      +/-   ##
==========================================
- Coverage   83.91%   83.59%   -0.32%     
==========================================
  Files          21       21              
  Lines        3084     3085       +1     
==========================================
- Hits         2588     2579       -9     
- Misses        496      506      +10     

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[tamasgal]

@Moelf can you have a quick look at https://github.com/JuliaHEP/UnROOT.jl/actions/runs/13791698857/job/38572996044?pr=378 is the error related to this PR?

[tamasgal]

Ah no sorry, I see it was failing before.