Wrong rendering of app icon located into launched subfolder on macOS

[EdwardEisenhauer]

Bug description

After moving Zulip app icon to the subfolder it looks like the artefacts in #1109. Outside the subfolder it renders properly.

To Reproduce

1. Download Zulip app for macOS and install it.
2. Move Zulip icon located in Launchpad to the subfolder.

Expected behavior

Zulip icon should render properly inside the subfolder icon.

Screenshots

Desktop:

• Machine: MacBookPro 13" Retina early 2015
• Operating System: macOS BigSur 11.4
• Zulip Desktop Version: v5.7.0

Additional context

This is a freshly installed (couple of days) OS. Everything else works just fine.