✨ Replace dict by Mapping on HTTPException.headers (fastapi#12997)

Co-authored-by: Alejandra <90076947+alejsdev@users.noreply.github.com>
Co-authored-by: Motov Yurii <109919500+YuriiMotov@users.noreply.github.com>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

Author: 4 people

fastapi/exceptions.py

@@ -1,4 +1,4 @@
-from collections.abc import Sequence
+from collections.abc import Mapping, Sequence
 from typing import Annotated, Any, Optional, TypedDict, Union
 
 from annotated_doc import Doc
@@ -68,7 +68,7 @@ def __init__(
             ),
         ] = None,
         headers: Annotated[
-            Optional[dict[str, str]],
+            Optional[Mapping[str, str]],
             Doc(
                 """
                 Any headers to send to the client in the response.