Update rattler-build version constraint in pixi.toml

Author: WhiteSymmetry

pixi.toml

@@ -19,7 +19,7 @@ setuptools = ">=82.0.1"
 wheel = ">=0.47.0"
 hatchling = ">=1.29.0"
 setuptools_scm = ">=9.2.2"
-rattler-build = ">=0.67.0,<0.68"
+rattler-build = ">=0.67.0"
 numpy = ">=2.4.6"
 pandas = ">=3.0.3"
 scipy = ">=1.18.0"