fix: reduce size of wheels by excluding generated .c files

[bdraco]

No description provided.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (4de31a3) 83.61% compared to head (7adb778) 83.40%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #262      +/-   ##
==========================================
- Coverage   83.61%   83.40%   -0.22%     
==========================================
  Files          28       28              
  Lines        3290     3290              
  Branches      682      682              
==========================================
- Hits         2751     2744       -7     
- Misses        326      330       +4     
- Partials      213      216       +3     

Files	Coverage Δ
src/dbus_fast/__version__.py	0.00% <0.00%> (ø)

... and 2 files with indirect coverage changes

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