Allow override file_size in response.sendfile

[nggit]

This will allow partial downloading. e.g. want to avoid zeros in sparse files.

[codecov[bot]]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (40d9241) 92.34% compared to head (8b2470c) 92.18%. Report is 3 commits behind head on master.

Files	Patch %	Lines
tremolo/lib/http_protocol.py	0.00%	3 Missing :warning:
tremolo/asgi_lifespan.py	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #57 +/- ## ========================================== - Coverage 92.34% 92.18% -0.17% ========================================== Files 19 19 Lines 1869 1881 +12 ========================================== + Hits 1726 1734 +8 - Misses 143 147 +4 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues

Measures
0 Security Hotspots
33.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud