Use explicit _GLibCVersion tuple

This addresses some type mismatches between `_GLibCVersion` and `tuple[int, int]`

Author: cthoyt

src/packaging/_manylinux.py

@@ -150,7 +150,7 @@ def _glibc_version_string() -> str | None:
     return _glibc_version_string_confstr() or _glibc_version_string_ctypes()
 
 
-def _parse_glibc_version(version_str: str) -> tuple[int, int]:
+def _parse_glibc_version(version_str: str) -> _GLibCVersion:
     """Parse glibc version.
 
     We use a regexp instead of str.split because we want to discard any
@@ -165,15 +165,15 @@ def _parse_glibc_version(version_str: str) -> tuple[int, int]:
             RuntimeWarning,
             stacklevel=2,
         )
-        return -1, -1
-    return int(m.group("major")), int(m.group("minor"))
+        return _GLibCVersion(-1, -1)
+    return _GLibCVersion(int(m.group("major")), int(m.group("minor")))
 
 
 @functools.lru_cache
-def _get_glibc_version() -> tuple[int, int]:
+def _get_glibc_version() -> _GLibCVersion:
     version_str = _glibc_version_string()
     if version_str is None:
-        return (-1, -1)
+        return _GLibCVersion(-1, -1)
     return _parse_glibc_version(version_str)
 
 
@@ -204,13 +204,13 @@ def _is_compatible(arch: str, version: _GLibCVersion) -> bool:
     return True
 
 
-_LEGACY_MANYLINUX_MAP = {
+_LEGACY_MANYLINUX_MAP: dict[_GLibCVersion, str] = {
     # CentOS 7 w/ glibc 2.17 (PEP 599)
-    (2, 17): "manylinux2014",
+    _GLibCVersion(2, 17): "manylinux2014",
     # CentOS 6 w/ glibc 2.12 (PEP 571)
-    (2, 12): "manylinux2010",
+    _GLibCVersion(2, 12): "manylinux2010",
     # CentOS 5 w/ glibc 2.5 (PEP 513)
-    (2, 5): "manylinux1",
+    _GLibCVersion(2, 5): "manylinux1",
 }