Make project version metadata dynamic

This reduces the places one needs to update a version string.

Author: QuLogic

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "cycler"
-version = "0.12.0.dev0"
+dynamic = ["version"]
 description = "Composable style cycles"
 authors = [
     {name = "Thomas A Caswell", email = "matplotlib-users@python.org"},
@@ -28,6 +28,9 @@ repository = "https://github.com/matplotlib/cycler"
 [tool.setuptools]
 packages = ["cycler"]
 
+[tool.setuptools.dynamic]
+version = {attr = "cycler.__version__"}
+
 [build-system]
 requires = ["setuptools>=61"]
 build-backend = "setuptools.build_meta"