[openpyxl] Remove unnecessary overload (#14201)

Author: srittau

stubs/openpyxl/openpyxl/styles/colors.pyi

@@ -66,11 +66,9 @@ class ColorDescriptor(Typed[Color, _N]):
         self: ColorDescriptor[Literal[False]], name: str | None = None, *, allow_none: Literal[False] = False
     ) -> None: ...
     @overload
-    def __set__(self: ColorDescriptor[_N], instance: Serialisable | Strict, value: str) -> None: ...
+    def __set__(self: ColorDescriptor[Literal[True]], instance: Serialisable | Strict, value: str | Color | None) -> None: ...
     @overload
-    def __set__(self: ColorDescriptor[Literal[True]], instance: Serialisable | Strict, value: Color | None) -> None: ...
-    @overload
-    def __set__(self: ColorDescriptor[Literal[False]], instance: Serialisable | Strict, value: Color) -> None: ...
+    def __set__(self: ColorDescriptor[Literal[False]], instance: Serialisable | Strict, value: str | Color) -> None: ...
 
 class RgbColor(Serialisable):
     tagname: ClassVar[str]