Fix spelling of iconUrl in the Squirrel maker config

[sergeichestakov]

Why

This is causing the Electron Icon to appear next to the app when listed in the "Programs and features" and "Installed apps" sections on Windows. Fixes WS-600

I thought I fixed this in https://github.com/replit/desktop/pull/37 but it turns out that I got the spelling wrong 🤦

Apparently, that's a fairly common issue: https://github.com/electron/forge/issues/2941#issuecomment-1261255135

What changed

Fix spelling of iconUrl in the Squirrel maker config

Test plan

Should see our own icon instead of Electron in those places after the next build

[sergeichestakov]

Screenshots for reference:

[linear[bot]]

WS-600 Still seeing Electron icon in Windows launch menu

See [thread](https://discord.com/channels/1077728434064740405/1111756232940859392/1132692706041266237)

[sergeichestakov]

gonna go ahead and land this since it's a simple config change but feel free to do a retroactive review

[sergeichestakov]

confirmed this now works in the latest release: