Third-party stubs: import from collections.abc where possible (#7637)

stubs/Markdown/markdown/blockparser.pyi

@@ -1,4 +1,5 @@
-from typing import Any, Iterable, TypeVar
+from collections.abc import Iterable
+from typing import Any, TypeVar
 from xml.etree.ElementTree import Element, ElementTree
 
 from . import Markdown

stubs/Markdown/markdown/core.pyi

@@ -1,5 +1,6 @@
 from _typeshed import Self
-from typing import Any, BinaryIO, Callable, ClassVar, Mapping, Sequence, Text, TextIO
+from collections.abc import Callable, Mapping, Sequence
+from typing import Any, BinaryIO, ClassVar, Text, TextIO
 from typing_extensions import Literal
 from xml.etree.ElementTree import Element
 

stubs/Markdown/markdown/extensions/__init__.pyi

@@ -1,4 +1,5 @@
-from typing import Any, Mapping
+from collections.abc import Mapping
+from typing import Any
 
 from markdown.core import Markdown