Apply some ruff suggestions

RUF100 Unused blanket `noqa` directive
RUF100 Unused `noqa` directive (non-enabled: `N818`)

src/packaging/_manylinux.py

@@ -174,7 +174,7 @@ def _is_compatible(arch: str, version: _GLibCVersion) -> bool:
         return False
     # Check for presence of _manylinux module.
     try:
-        import _manylinux  # noqa
+        import _manylinux
     except ImportError:
         return True
     if hasattr(_manylinux, "manylinux_compatible"):

src/packaging/metadata.py

@@ -44,7 +44,7 @@ def __init_subclass__(*_args, **_kwargs):
     ExceptionGroup
 except NameError:  # pragma: no cover
 
-    class ExceptionGroup(Exception):  # noqa: N818
+    class ExceptionGroup(Exception):
         """A minimal implementation of :external:exc:`ExceptionGroup` from Python 3.11.
 
         If :external:exc:`ExceptionGroup` is already defined by Python itself,