Fix patch styling type hints

This change is not strictly correct, as these style classes don't
actually inherit from the surrounding class, but it allows one to pass
an instance of the style classes directly.

Author: QuLogic

lib/matplotlib/patches.pyi

@@ -328,7 +328,7 @@ class _Style:
     def register(cls, name: str, style: type) -> None: ...
 
 class BoxStyle(_Style):
-    class Square:
+    class Square(BoxStyle):
         pad: float
         def __init__(self, pad: float = ...) -> None: ...
         def __call__(
@@ -340,7 +340,7 @@ class BoxStyle(_Style):
             mutation_size: float,
         ) -> Path: ...
 
-    class Circle:
+    class Circle(BoxStyle):
         pad: float
         def __init__(self, pad: float = ...) -> None: ...
         def __call__(
@@ -352,7 +352,7 @@ class BoxStyle(_Style):
             mutation_size: float,
         ) -> Path: ...
 
-    class Ellipse:
+    class Ellipse(BoxStyle):
         pad: float
         def __init__(self, pad: float = ...) -> None: ...
         def __call__(
@@ -364,7 +364,7 @@ class BoxStyle(_Style):
             mutation_size: float,
         ) -> Path: ...
 
-    class LArrow:
+    class LArrow(BoxStyle):
         pad: float
         def __init__(self, pad: float = ...) -> None: ...
         def __call__(
@@ -386,7 +386,7 @@ class BoxStyle(_Style):
             mutation_size: float,
         ) -> Path: ...
 
-    class DArrow:
+    class DArrow(BoxStyle):
         pad: float
         def __init__(self, pad: float = ...) -> None: ...
         def __call__(
@@ -398,7 +398,7 @@ class BoxStyle(_Style):
             mutation_size: float,
         ) -> Path: ...
 
-    class Round:
+    class Round(BoxStyle):
         pad: float
         rounding_size: float | None
         def __init__(
@@ -413,7 +413,7 @@ class BoxStyle(_Style):
             mutation_size: float,
         ) -> Path: ...
 
-    class Round4:
+    class Round4(BoxStyle):
         pad: float
         rounding_size: float | None
         def __init__(
@@ -428,7 +428,7 @@ class BoxStyle(_Style):
             mutation_size: float,
         ) -> Path: ...
 
-    class Sawtooth:
+    class Sawtooth(BoxStyle):
         pad: float
         tooth_size: float | None
         def __init__(
@@ -454,7 +454,7 @@ class BoxStyle(_Style):
         ) -> Path: ...
 
 class ConnectionStyle(_Style):
-    class _Base:
+    class _Base(ConnectionStyle):
         class SimpleEvent:
             def __init__(self, xy: tuple[float, float]) -> None: ...
 
@@ -529,7 +529,7 @@ class ConnectionStyle(_Style):
         ) -> Path: ...
 
 class ArrowStyle(_Style):
-    class _Base:
+    class _Base(ArrowStyle):
         @staticmethod
         def ensure_quadratic_bezier(path: Path) -> list[float]: ...
         def transmute(