Formally drop python 3.8 support (microsoft#2354)

Python 3.8 has reached EOL.

Fix microsoft#2233

Author: justinchuby

pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = ["setuptools>=61.0.0"]
+requires = ["setuptools>=70.0.0"]
 build-backend = "setuptools.build_meta"
 
 [project]
@@ -8,7 +8,7 @@ dynamic = ["version", "urls"]
 description = "Naturally author ONNX functions and models using a subset of Python"
 authors = [{ name = "Microsoft Corporation", email = "[email protected]" }]
 readme = "README.md"
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 license = { file = "LICENSE" }
 classifiers = [
   "Development Status :: 4 - Beta",
@@ -17,7 +17,6 @@ classifiers = [
   "Operating System :: POSIX",
   "Operating System :: MacOS :: MacOS X",
   "Operating System :: Microsoft :: Windows",
-  "Programming Language :: Python :: 3.8",
   "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
@@ -108,18 +107,6 @@ warn_no_return = true
 warn_unused_configs = true
 warn_unused_ignores = false
 
-[tool.black]
-target-version = ["py39", "py310", "py311"]
-# Black's extend-exclude needs to be a regex string
-extend-exclude = "/tests/models|/tests/onnx_backend_test_code"
-line-length = 95
-
-[tool.isort]
-profile = "black"
-extend_skip_glob = [
-  "tests/onnx_backend_test_code/*.py",
-]
-
 [tool.pylint.messages_control]
 # NOTE: This list is for vscode. Add new disables in pyproject_pylint.toml for lintrunner
 # Exclude patterns should be modified in .lintrunner.toml