Adopt PEP-621 for packaging

.flake8

@@ -0,0 +1,15 @@
+[flake8]
+max-line-length = 100
+# E203 conflicts with PEP8; see https://github.com/psf/black#slices
+extend-ignore = E203
+
+# flake8-pytest-style
+# PT001:
+pytest-fixture-no-parentheses = true
+# PT006:
+pytest-parametrize-names-type = tuple
+# PT007:
+pytest-parametrize-values-type = tuple
+pytest-parametrize-values-row-type = tuple
+# PT023:
+pytest-mark-no-parentheses = true

pyproject.toml

@@ -1,5 +1,119 @@
 [build-system]
-requires = ["setuptools>=45", "setuptools_scm[toml]>=6.2"]
+requires = ["setuptools>=63", "setuptools_scm[toml]>=7"]
 build-backend = "setuptools.build_meta"
 
+[project]
+# https://peps.python.org/pep-0621/#readme
+requires-python = ">=3.7"
+dynamic = ["version"]
+name = "pip-tools"
+description = "pip-tools keeps your pinned dependencies fresh."
+readme = "README.rst"
+authors = [{ "name" = "Vincent Driessen", "email" = "[email protected]" }]
+license = { text = "BSD" }
+classifiers = [
+  "Development Status :: 5 - Production/Stable",
+  "Environment :: Console",
+  "Intended Audience :: Developers",
+  "Intended Audience :: System Administrators",
+  "License :: OSI Approved :: BSD License",
+  "Operating System :: OS Independent",
+  "Programming Language :: Python :: 3 :: Only",
+  "Programming Language :: Python :: 3",
+  "Programming Language :: Python :: 3.10",
+  "Programming Language :: Python :: 3.11",
+  "Programming Language :: Python :: 3.7",
+  "Programming Language :: Python :: 3.8",
+  "Programming Language :: Python :: 3.9",
+  "Programming Language :: Python :: Implementation :: CPython",
+  "Programming Language :: Python :: Implementation :: PyPy",
+  "Programming Language :: Python",
+  "Topic :: Software Development :: Quality Assurance",
+  "Topic :: Software Development :: Testing",
+  "Topic :: System :: Systems Administration",
+  "Topic :: Utilities",
+  "Typing :: Typed",
+]
+keywords = ["pip", "requirements", "packaging"]
+dependencies = [
+    # direct dependencies
+    "build",
+    "click >= 8",
+    "pip >= 22.2",
+    # indirect dependencies
+    "setuptools",  # typically needed when pip-tools invokes setup.py
+    "wheel",  # pip plugin needed by pip-tools
+]
+
+[project.urls]
+homepage = "https://github.com/jazzband/pip-tools/"
+documentation = "https://pip-tools.readthedocs.io/en/latest/"
+repository = "https://github.com/jazzband/pip-tools"
+changelog = "https://github.com/jazzband/pip-tools/releases"
+
+[project.optional-dependencies]
+testing = [
+    "pytest >= 7.2.0",
+    "pytest-rerunfailures",
+    "pytest-xdist",
+    # build deps for tests
+    "flit_core >=2,<4",
+    "poetry_core>=1.0.0",
+]
+coverage = [
+    "pytest-cov",
+]
+
+[project.scripts]
+pip-compile = "piptools.scripts.compile:cli"
+pip-sync = "piptools.scripts.sync:cli"
+
+[tool.isort]
+profile = "black"
+add_imports = "from __future__ import annotations"
+
+[tool.mypy]
+disallow_untyped_defs = true
+disallow_any_generics = true
+disallow_incomplete_defs = true
+disallow_subclassing_any = true
+disallow_untyped_calls = true
+disallow_untyped_decorators = true
+ignore_missing_imports = true
+no_implicit_optional = true
+no_implicit_reexport = true
+strict_equality = true
+warn_redundant_casts = true
+warn_return_any = true
+warn_unused_configs = true
+warn_unused_ignores = true
+
+# Avoid error: Duplicate module named 'setup'
+# https://github.com/python/mypy/issues/4008
+exclude = "^tests/test_data/"
+
+[tool.mypy.overrides]
+modules = [
+    "tests.*"
+]
+disallow_untyped_defs = false
+
+[tool.pytest.ini_options]
+addopts = [
+    # `pytest-xdist`:
+    "--numprocesses=auto"
+]
+norecursedirs = ".* build dist venv test_data piptools/_compat/*"
+testpaths = "tests piptools"
+filterwarnings = [
+    "always"
+]
+markers = [
+    "network: mark tests that require internet access"
+]
+
+[tool.setuptools.packages.find]
+# needed only because we did not adopt src layout yet
+exclude = ["img"]
+
 [tool.setuptools_scm]

tox.ini

@@ -22,8 +22,11 @@ commands_pre =
     pip --version
 commands = pytest {posargs}
 passenv =
-    CI
-    GITHUB_ACTIONS
+  CI
+  GITHUB_ACTIONS
+  PY_COLORS
+  PY_FORCE_COLOR
+  PRE_COMMIT_COLOR
 pip_pre=True
 
 [testenv:checkqa]
@@ -41,7 +44,7 @@ deps =
 commands_pre =
 commands =
     python -m build --outdir {envtmpdir} --sdist {toxinidir}
-    twine check {envtmpdir}{/}*
+    twine check --strict {envtmpdir}{/}*
 skip_install = true
 
 [testenv:build-docs]