Typing: return Self in stdlib.BoundLogger (#694)

* Typing: use Self in BoundLogger

* Fix missing import

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

for more information, see https://pre-commit.ci

* Fix Self import for Python < 3.11

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Hynek Schlawack <[email protected]>

src/structlog/stdlib.py

@@ -21,6 +21,13 @@
 from functools import partial
 from typing import Any, Callable, Collection, Dict, Iterable, Sequence, cast
 
+
+if sys.version_info >= (3, 11):
+    from typing import Self
+else:
+    from typing_extensions import Self
+
+
 from . import _config
 from ._base import BoundLoggerBase
 from ._frames import _find_first_app_frame_and_name, _format_stack
@@ -155,13 +162,13 @@ class BoundLogger(BoundLoggerBase):
 
     _logger: logging.Logger
 
-    def bind(self, **new_values: Any) -> BoundLogger:
+    def bind(self, **new_values: Any) -> Self:
         """
         Return a new logger with *new_values* added to the existing ones.
         """
         return super().bind(**new_values)
 
-    def unbind(self, *keys: str) -> BoundLogger:
+    def unbind(self, *keys: str) -> Self:
         """
         Return a new logger with *keys* removed from the context.
 
@@ -170,15 +177,15 @@ def unbind(self, *keys: str) -> BoundLogger:
         """
         return super().unbind(*keys)
 
-    def try_unbind(self, *keys: str) -> BoundLogger:
+    def try_unbind(self, *keys: str) -> Self:
         """
         Like :meth:`unbind`, but best effort: missing keys are ignored.
 
         .. versionadded:: 18.2.0
         """
         return super().try_unbind(*keys)
 
-    def new(self, **new_values: Any) -> BoundLogger:
+    def new(self, **new_values: Any) -> Self:
         """
         Clear context and binds *initial_values* using `bind`.