Update Nightly app icon (#35215)

Danilo Leal created 

Follow-up to https://github.com/zed-industries/zed/pull/35119.

Release Notes:

- N/A

Change summary

crates/zed/resources/app-icon-nightly.png    | 0 
crates/zed/resources/app-icon-nightly@2x.png | 0 
2 files changed

Detailed changes