fix(pyproject): update version from 0.8.9 to 0.9.0 in configuration files

Author: Akagi201

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "uv_build"
 
 [project]
 name = "pb-spec"
-version = "0.8.9"
+version = "0.9.0"
 description = "Plan-Build Spec (pb-spec): A CLI tool for managing AI coding assistant skills"
 readme = "README.md"
 license = "Apache-2.0"