Improve file writing

[gerlero]

No description provided.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 28.57143% with 5 lines in your changes missing coverage. Please review.

Project coverage is 86.45%. Comparing base (156abc7) to head (9db8caa).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
foamlib/_files/_serialization.py	25.00%	3 Missing ⚠️
foamlib/_files/_files.py	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #259      +/-   ##
==========================================
- Coverage   86.69%   86.45%   -0.24%     
==========================================
  Files          16       16              
  Lines        1345     1351       +6     
==========================================
+ Hits         1166     1168       +2     
- Misses        179      183       +4     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.