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

stubs/Pygments/pygments/formatters/__init__.pyi

@@ -1,4 +1,5 @@
-from typing import Any, Generator
+from collections.abc import Generator
+from typing import Any
 
 from ..formatter import Formatter
 from .bbcode import BBCodeFormatter as BBCodeFormatter

stubs/Pygments/pygments/plugin.pyi

@@ -1,4 +1,5 @@
-from typing import Any, Generator, Iterable
+from collections.abc import Generator, Iterable
+from typing import Any
 
 from pkg_resources import EntryPoint
 from pygments.filter import Filter