Revert "Add osx-64 to the pixi config." (#11203)

This reverts commit cf6bf5b.

Author: VeckoTheGecko

pixi.toml

@@ -1,7 +1,7 @@
 [workspace]
 preview = ["pixi-build"]
 channels = ["conda-forge", "nodefaults"]
-platforms = ["win-64", "linux-64", "osx-arm64", "osx-64"]
+platforms = ["win-64", "linux-64", "osx-arm64"]
 requires-pixi = ">=0.63.2"
 
 [package]