fix: restore Python 3.7 support

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

cibuildwheel/_compat/typing.py

@@ -0,0 +1,50 @@
+from __future__ import annotations
+
+import os
+import subprocess
+import sys
+from typing import TYPE_CHECKING, Union
+
+if sys.version_info < (3, 8):
+    from typing_extensions import Final, Literal, OrderedDict, Protocol, TypedDict
+else:
+    from typing import Final, Literal, OrderedDict, Protocol, TypedDict  # noqa: TID251
+
+if sys.version_info < (3, 11):
+    from typing_extensions import NotRequired, assert_never
+else:
+    from typing import NotRequired, assert_never  # noqa: TID251
+
+__all__ = (
+    "Final",
+    "Literal",
+    "PLATFORMS",
+    "PathOrStr",
+    "PlatformName",
+    "Protocol",
+    "PLATFORMS",
+    "PopenBytes",
+    "Protocol",
+    "TypedDict",
+    "OrderedDict",
+    "assert_never",
+    "NotRequired",
+)
+
+
+if TYPE_CHECKING:
+    PopenBytes = subprocess.Popen[bytes]
+    PathOrStr = Union[str, os.PathLike[str]]
+else:
+    PopenBytes = subprocess.Popen
+    PathOrStr = Union[str, "os.PathLike[str]"]
+
+
+PlatformName = Literal["linux", "macos", "windows"]
+PLATFORMS: Final[set[PlatformName]] = {"linux", "macos", "windows"}
+
+
+class GenericPythonConfiguration(Protocol):
+    @property
+    def identifier(self) -> str:
+        ...