[stdlib] Deprecate old functions (#14553)

* [stdlib] Deprecate many functions

* Fix typo

* Imporove message for asyncio/trsock

* Apply suggestions from code review

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

* Add Python before version

* [pre-commit.ci] auto fixes from pre-commit.com hooks

* Wrap comment lines

* fix the rest

---------

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

stdlib/gzip.pyi

@@ -3,7 +3,7 @@ import zlib
 from _typeshed import ReadableBuffer, SizedBuffer, StrOrBytesPath, WriteableBuffer
 from io import FileIO, TextIOWrapper
 from typing import Final, Literal, Protocol, overload, type_check_only
-from typing_extensions import TypeAlias
+from typing_extensions import TypeAlias, deprecated
 
 if sys.version_info >= (3, 14):
     from compression._common._streams import BaseStream, DecompressReader
@@ -143,6 +143,7 @@ class GzipFile(BaseStream):
     ) -> None: ...
     if sys.version_info < (3, 12):
         @property
+        @deprecated("Deprecated since Python 2.6; removed in Python 3.12. Use `name` attribute instead.")
         def filename(self) -> str: ...
 
     @property