Add mypy ignores for attributes not available on Py3.9.

Author: freakboy3742

mesonpy/__init__.py

@@ -720,7 +720,7 @@ def __init__(
                     self._meson_cross_file.write_text(cross_file_data, encoding='utf-8')
                     self._meson_args['setup'].extend(('--cross-file', os.fspath(self._meson_cross_file)))
         elif sysconfig.get_platform().startswith('ios-'):
-            ios_ver = platform.ios_ver()
+            ios_ver = platform.ios_ver()  # type: ignore[attr-defined]
 
             arch = platform.machine()
             family = 'aarch64' if arch == 'arm64' else arch

mesonpy/_tags.py

@@ -166,7 +166,7 @@ def _get_ios_platform_tag() -> str:
     try:
         version = tuple(map(int, os.environ.get('IPHONEOS_DEPLOYMENT_TARGET', '').split('.')))[:2]
     except ValueError:
-        version = tuple(map(int, platform.ios_ver().release.split('.')))[:2]
+        version = tuple(map(int, platform.ios_ver().release.split('.')))[:2]  # type: ignore[attr-defined]
 
     # Although _multiarch is an internal implementation detail, it's a core part
     # of how CPython is implemented on iOS; this attribute is also relied upon