[web] fix image avatar image being stretched

Summary: As I was working on enabling avatars on web, I noticed that the image avatars were slightly stretched. This diff fixes this issue

Test Plan:
Please see the screenshots below to see the changes I made

Before:

After:

For reference this is what image avatars look like on native which now matches the after photo:

Reviewers: atul, ashoat

Reviewed By: ashoat

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D7639