Add missing chipflow pdm script

Author: robtaylor

pyproject.toml

@@ -72,7 +72,7 @@ test-docs.cmd = "sphinx-build -b doctest docs/ docs/_build"
 lint.cmd = "ruff check"
 docs.cmd = "sphinx-build docs/ docs/_build/ -W --keep-going"
 test-silicon.cmd = "pytest tests/test_silicon_platform.py tests/test_silicon_platform_additional.py tests/test_silicon_platform_amaranth.py tests/test_silicon_platform_build.py tests/test_silicon_platform_port.py --cov=chipflow_lib.platforms.silicon --cov-report=term"
-
+chipflow.cmd = "chipflow"
 
 [dependency-groups]
 lint = [