Fix the small error of type in geometric source (#5561)

pyvista/core/utilities/geometric_sources.py

@@ -197,7 +197,7 @@ def height(self, height: float):
         self.SetHeight(height)
 
     @property
-    def radius(self) -> bool:
+    def radius(self) -> float:
         """Get base radius of the cone.
 
         Returns