add noxfile to run python linters and pip-compile

Currently, this only lints the noxfile itself and the issue labeler
script.
We can expand the noxfile to build docs and lint other new files in
hacking.

Relates: ansible#54

.isort.cfg

@@ -0,0 +1,2 @@
+[isort]
+profile = black

noxfile.py

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+import os
+from pathlib import Path
+
+import nox
+
+LINT_FILES = ("hacking/pr_labeler/label.py", "noxfile.py")
+PINNED = os.environ.get("PINNED", "true").lower() in {"1", "true"}
+nox.options.sessions = ("lint",)
+
+
+def install(session: nox.Session, *args, req: str, **kwargs):
+    if PINNED:
+        kwargs.setdefault("env", {})["PIP_CONSTRAINT"] = f"tests/{req}.txt"
+    session.install("-r", f"tests/{req}.in", *args, **kwargs)
+
+
+@nox.session
+def static(session: nox.Session):
+    """
+    Run static checkers
+    """
+    install(session, req="static")
+    session.run("ruff", *session.posargs, *LINT_FILES)
+
+
+@nox.session
+def formatters(session: nox.Session):
+    """
+    Reformat code
+    """
+    install(session, req="formatters")
+    session.run("isort", *session.posargs, *LINT_FILES)
+    session.run("black", *session.posargs, *LINT_FILES)
+
+
+@nox.session
+def formatters_check(session: nox.Session):
+    """
+    Check code formatting without making changes
+    """
+    install(session, req="formatters")
+    session.run("isort", "--check", *session.posargs, *LINT_FILES)
+    session.run("black", "--check", *session.posargs, *LINT_FILES)
+
+
+@nox.session
+def typing(session: nox.Session):
+    install(session, req="typing")
+    session.run("mypy", *session.posargs, *LINT_FILES)
+
+
+@nox.session
+def lint(session: nox.Session):
+    session.notify("static")
+    session.notify("formatters")
+
+
+requirements_files = list(
+    {path.name.replace(".in", "") for path in Path("tests").glob("*in")}
+    - {"constraints", "constraints-base"}
+)
+
+
+@nox.session(name="pip-compile", python=["3.10"])
+@nox.parametrize(["req"], requirements_files, requirements_files)
+def pip_compile(session: nox.Session, req: str):
+    session.install("pip-tools")
+    # fmt: off
+    session.run(
+        "pip-compile",
+        "--resolver", "backtracking",
+        "--upgrade",
+        "--allow-unsafe",
+        "--quiet",
+        "--strip-extras",
+        "--output-file", f"tests/{req}.txt",
+        f"tests/{req}.in",
+    )
+    # fmt: on

tests/formatters.in

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+black
+isort

tests/formatters.txt

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+#
+# This file is autogenerated by pip-compile with Python 3.10
+# by the following command:
+#
+#    pip-compile --allow-unsafe --output-file=tests/formatters.txt --strip-extras tests/formatters.in
+#
+black==23.7.0
+    # via -r tests/formatters.in
+click==8.1.6
+    # via black
+isort==5.12.0
+    # via -r tests/formatters.in
+mypy-extensions==1.0.0
+    # via black
+packaging==23.1
+    # via black
+pathspec==0.11.2
+    # via black
+platformdirs==3.10.0
+    # via black
+tomli==2.0.1
+    # via black

tests/static.in

@@ -0,0 +1 @@
+ruff

tests/static.txt

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+#
+# This file is autogenerated by pip-compile with Python 3.10
+# by the following command:
+#
+#    pip-compile --allow-unsafe --output-file=tests/static.txt --strip-extras tests/static.in
+#
+ruff==0.0.284
+    # via -r tests/static.in

tests/typing.in

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+-r ../hacking/pr_labeler/requirements.txt
+mypy
+nox

tests/typing.txt

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+#
+# This file is autogenerated by pip-compile with Python 3.10
+# by the following command:
+#
+#    pip-compile --allow-unsafe --output-file=tests/typing.txt --strip-extras tests/typing.in
+#
+argcomplete==3.1.1
+    # via nox
+certifi==2023.7.22
+    # via requests
+cffi==1.15.1
+    # via
+    #   cryptography
+    #   pynacl
+charset-normalizer==3.2.0
+    # via requests
+click==8.1.6
+    # via typer
+codeowners==0.6.0
+    # via -r tests/../hacking/pr_labeler/requirements.txt
+colorlog==6.7.0
+    # via nox
+cryptography==41.0.3
+    # via pyjwt
+deprecated==1.2.14
+    # via pygithub
+distlib==0.3.7
+    # via virtualenv
+filelock==3.12.2
+    # via virtualenv
+idna==3.4
+    # via requests
+mypy==1.5.0
+    # via -r tests/typing.in
+mypy-extensions==1.0.0
+    # via mypy
+nox==2023.4.22
+    # via -r tests/typing.in
+packaging==23.1
+    # via nox
+platformdirs==3.10.0
+    # via virtualenv
+pycparser==2.21
+    # via cffi
+pygithub==1.59.1
+    # via -r tests/../hacking/pr_labeler/requirements.txt
+pyjwt==2.8.0
+    # via pygithub
+pynacl==1.5.0
+    # via pygithub
+requests==2.31.0
+    # via pygithub
+tomli==2.0.1
+    # via mypy
+typer==0.9.0
+    # via -r tests/../hacking/pr_labeler/requirements.txt
+typing-extensions==4.7.1
+    # via
+    #   codeowners
+    #   mypy
+    #   typer
+urllib3==2.0.4
+    # via requests
+virtualenv==20.24.2
+    # via nox
+wrapt==1.15.0
+    # via deprecated