fix(bar): give ProgressBarBase an explicit __del__ chain (CodeQL missing-call-to-delete)

CodeQL flagged ProgressBarBase (Iterable + ProgressBarMixinBase multiple
inheritance) for finalizing without an explicit __del__ calling the base
finalizer. Revert the earlier wrong-class guarded super().__del__() in
ProgressBarMixinBase and define ProgressBarBase.__del__ = super().__del__(),
which resolves to the same ProgressBarMixinBase.__del__ reached by
inheritance — behaviourally identical, MI chain now explicit.

Author: wolph

progressbar/bar.py

@@ -175,13 +175,6 @@ def __del__(self):
             except Exception:  # noqa: BLE001, S110
                 pass
 
-        # Cooperatively chain to a superclass finalizer when one exists. This
-        # class's bases (abc.ABC, object) define no __del__, so the call is a
-        # no-op today; the guard keeps finalization cooperative — and avoids
-        # an AttributeError — should a base with __del__ ever be introduced.
-        if hasattr(super(), '__del__'):  # pragma: no cover
-            super().__del__()  # pyright: ignore[reportAttributeAccessIssue]
-
     def __getstate__(self):
         return self.__dict__
 
@@ -214,6 +207,15 @@ def __repr__(self):
         label = f': {self.label}' if self.label else ''
         return f'<{self.__class__.__name__}#{self.index}{label}>'
 
+    def __del__(self) -> None:
+        # ProgressBarBase mixes collections.abc.Iterable in alongside
+        # ProgressBarMixinBase (which defines the real finalizer). Define
+        # __del__ here so that finalizer is reached explicitly through the MRO
+        # instead of only by attribute inheritance — behaviourally identical
+        # (super() resolves to the same ProgressBarMixinBase.__del__), but it
+        # makes the multiple-inheritance finalizer chain unambiguous.
+        super().__del__()  # pragma: no cover
+
 
 class DefaultFdMixin(ProgressBarMixinBase):
     # The file descriptor to write to. Defaults to `sys.stderr`