fix(avatars): fix egg shaped avatars (#5420) r=@shane-tomlinson
fix(avatars): fix egg shaped avatars (#5420) r=@shane-tomlinson

Fixes #5011 

Nice, simple fix @vladikoff, thanks!
mozilla/fxa-content-server,shane-tomlinson/fxa-content-server,shane-tomlinson/fxa-content-server,shane-tomlinson/fxa-content-server,mozilla/fxa-content-server,mozilla/fxa-content-server