feat: speed up readers in the unmarshall path

[bdraco]

No description provided.

[codecov]

Codecov Report

Patch coverage: 75.00% and project coverage change: -0.04% ⚠️

Comparison is base (0b6ba93) 83.32% compared to head (2936d2e) 83.29%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #253      +/-   ##
==========================================
- Coverage   83.32%   83.29%   -0.04%     
==========================================
  Files          28       28              
  Lines        3269     3269              
  Branches      678      678              
==========================================
- Hits         2724     2723       -1     
  Misses        330      330              
- Partials      215      216       +1     

Files Changed	Coverage Δ
src/dbus_fast/__version__.py	0.00% <0.00%> (ø)
src/dbus_fast/_private/unmarshaller.py	94.97% <100.00%> (+0.23%)	⬆️

... and 1 file with indirect coverage changes

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[bdraco]

CI seems happy. cython had a lot of bugs with cdef void before but they all appear to be fixed 🤞