<BaseAvatar/>'s SVG rendering is buggy on Safari

[MichaelSun48]

Environment

SaaS (https://sentry.io/)

Steps to Reproduce

Using Safari, view (for example) the replays tab and pay attention to the avatars:

Notice how the top of the circle is flattened and the letter is slightly misaligned, which is caused by the rendering of the circle being slightly larger than expected and being cut off by the border. This seems to occur across most usages of <LetterAvatar/> and <BaseAvatar/>

When fixing, remember to update avatar.py on the backend as well, since this file (for some reason) seems like it needs to be updated whenever LetterAvatar is changed