inline blame: Match icon size to font size in buffer (#11788)
This fixes #11311.
Release Notes:
- Fixed icon in inline git blame entry not changing with the buffer font
size. ([#11311](https://github.com/zed-industries/zed/issues/11311)).
Before:

After:

ec65035659Thorsten Ball committed on 5/14/2024, 9:06:16 AM· committed by GitHubparent9b74acc