Declare Python 3.13 support

Author: adamchainz

pyproject.toml

@@ -36,6 +36,7 @@ classifiers = [
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
+  "Programming Language :: Python :: 3.13",
   "Typing :: Typed",
 ]
 dependencies = [
@@ -53,6 +54,9 @@ add_imports = [
 force_single_line = true
 profile = "black"
 
+[tool.pyproject-fmt]
+max_supported_python = "3.13"
+
 [tool.pytest.ini_options]
 addopts = """\
     --strict-config