Update Unused parameters in stubs/ (#9704)

* Update _Unused TypeAlias

* Update `object | None` params

* Replace unused `object` parameters with `Unused` alias

stubs/fpdf2/fpdf/html.pyi

@@ -1,4 +1,4 @@
-from _typeshed import Incomplete
+from _typeshed import Incomplete, Unused
 from collections.abc import Callable
 from html.parser import HTMLParser
 from logging import Logger
@@ -68,7 +68,7 @@ class HTML2FPDF(HTMLParser):
         ul_bullet_char: str = ...,
         heading_sizes: Incomplete | None = None,
         warn_on_tags_not_matching: bool = True,
-        **_: object,
+        **_: Unused,
     ): ...
     def width2unit(self, length): ...
     def handle_data(self, data) -> None: ...

stubs/fpdf2/fpdf/output.pyi

@@ -1,4 +1,4 @@
-from _typeshed import Incomplete
+from _typeshed import Incomplete, Unused
 from collections import defaultdict
 from logging import Logger
 from typing_extensions import Final
@@ -165,7 +165,7 @@ class PDFPagesRoot(PDFObject):
 
 class PDFExtGState(PDFObject):
     def __init__(self, dict_as_str) -> None: ...
-    def serialize(self, obj_dict: object = None, _security_handler: StandardSecurityHandler | None = None) -> str: ...
+    def serialize(self, obj_dict: Unused = None, _security_handler: StandardSecurityHandler | None = None) -> str: ...
 
 class PDFXrefAndTrailer(ContentWithoutID):
     output_builder: Incomplete

stubs/fpdf2/fpdf/structure_tree.pyi

@@ -1,4 +1,4 @@
-from _typeshed import Incomplete
+from _typeshed import Incomplete, Unused
 from collections import defaultdict
 from collections.abc import Generator, Iterable
 
@@ -8,7 +8,7 @@ from .syntax import PDFArray, PDFObject, PDFString
 class NumberTree(PDFObject):
     nums: defaultdict[Incomplete, list[Incomplete]]
     def __init__(self) -> None: ...
-    def serialize(self, obj_dict: object = ..., _security_handler: StandardSecurityHandler | None = None) -> str: ...
+    def serialize(self, obj_dict: Unused = None, _security_handler: StandardSecurityHandler | None = None) -> str: ...
 
 class StructTreeRoot(PDFObject):
     type: str