Bump version from 0.2.0 to 0.2.1 (#5)

Co-authored-by: Claude <noreply@anthropic.com>

Author: JBloss1517

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "dag-simple"
-version = "0.2.0"
+version = "0.2.1"
 description = "A dead simple, type-safe DAG (Directed Acyclic Graph) library with runtime validation, caching, and async support"
 readme = "README.md"
 requires-python = ">=3.10"