Relax upper bound for py-uv-build.

--- pyproject.toml.orig	1970-01-01 00:00:00 UTC
+++ pyproject.toml
@@ -1,6 +1,6 @@ build-backend = "uv_build"
 [build-system]
 build-backend = "uv_build"
-requires = ["uv_build>=0.9.6,<0.13.0"]
+requires = ["uv_build>=0.9.6"]
 
 [project]
 classifiers = [