chore: drop python 3.7 for cibuildwheel driver

This drops python 3.7 for cibuildwheel.
Building python 3.6 / 3.7 packages is still supported.

cibuildwheel/oci_container.py

@@ -14,9 +14,8 @@ from collections.abc import Mapping, Sequence
 from dataclasses import dataclass
 from pathlib import Path, PurePath, PurePosixPath
 from types import TracebackType
-from typing import IO, Dict
+from typing import IO, Dict, Literal
 
-from ._compat.typing import Literal
 from .typing import PathOrStr, PopenBytes
 from .util import CIProvider, detect_ci_provider, parse_key_value_string