Use union annotation syntax that came with Python 3.10

Author: stefanv

spin/__main__.py

@@ -6,7 +6,6 @@
 import sys
 import textwrap
 import traceback
-from typing import Union
 
 import click
 
@@ -31,7 +30,7 @@
 )
 
 
-def _detect_config_dir(path: pathlib.Path) -> Union[pathlib.Path, None]:
+def _detect_config_dir(path: pathlib.Path) -> pathlib.Path | None:
     path = path.resolve()
     files = os.listdir(path)
     if any(f in files for f in config_filenames):

spin/cmds/meson.py

@@ -8,7 +8,6 @@
 import sys
 from enum import Enum
 from pathlib import Path
-from typing import Union
 
 import click
 
@@ -36,7 +35,7 @@ def _meson_cli():
         return [meson_cli]
 
 
-def editable_install_path(distname: str) -> Union[str, None]:
+def editable_install_path(distname: str) -> str | None:
     """Return path of the editable install for package `distname`.
 
     If the package is not an editable install, return None.
@@ -191,15 +190,15 @@ def _get_site_packages(build_dir: str) -> str:
     return site_packages
 
 
-def _meson_version() -> Union[str, None]:
+def _meson_version() -> str | None:
     try:
         p = _run(_meson_cli() + ["--version"], output=False, echo=False)
         return p.stdout.decode("ascii").strip()
     except:
         return None
 
 
-def _meson_version_configured(build_dir: str) -> Union[str, None]:
+def _meson_version_configured(build_dir: str) -> str | None:
     try:
         meson_info_fn = os.path.join(build_dir, "meson-info", "meson-info.json")
         with open(meson_info_fn) as f: