Add temp nightly icon (#3488)

[[PR Description]]

This will get updated – I need to get the template derek used for the
new preview icon. Sorry for the jank in advance.

Release Notes:

- N/A

crates/zed/Cargo.toml

@@ -172,7 +172,7 @@ osx_info_plist_exts = ["resources/info/*"]
 osx_url_schemes = ["zed-dev"]
 
 [package.metadata.bundle-nightly]
-icon = ["resources/app-icon-preview@2x.png", "resources/app-icon-preview.png"]
+icon = ["resources/app-icon-nightly@2x.png", "resources/app-icon-nightly.png"]
 identifier = "dev.zed.Zed-Nightly"
 name = "Zed Nightly"
 osx_minimum_system_version = "10.15.7"

crates/zed2/Cargo.toml

@@ -167,7 +167,7 @@ osx_info_plist_exts = ["resources/info/*"]
 osx_url_schemes = ["zed-dev"]
 
 [package.metadata.bundle-nightly]
-icon = ["resources/app-icon-preview@2x.png", "resources/app-icon-preview.png"]
+icon = ["resources/app-icon-nightly@2x.png", "resources/app-icon-nightly.png"]
 identifier = "dev.zed.Zed-Dev"
 name = "Zed Nightly"
 osx_minimum_system_version = "10.15.7"