fix: make Psycopg3TracedAsyncCursor implementation conform to its type hints [backport 1.20] (#7914)

Backport a254b7a from #7908 to 1.20.

This pull request fixes
#7900 by aligning
`Psycopg3TracedAsyncCursor.__aexit__` with the method it wraps,
`AsyncCursor.__aexit__`. It removes a return value that is sometimes
non-`None`, breaking compatibility with psycopg3's interface.

No regression test because this is a straightforward alignment of
integration code with the integrated library's interface.

## Checklist

- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed. If no release note is required, add label
`changelog/no-changelog`.
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/)).
- [x] Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist

- [x] Title is accurate.
- [x] No unnecessary changes are introduced.
- [x] Description motivates each change.
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [x] Testing strategy adequately addresses listed risk(s).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] Release note makes sense to a user of the library.
- [x] Reviewer has explicitly acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment.
- [x] Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)
- [x] If this PR touches code that signs or publishes builds or
packages, or handles credentials of any kind, I've requested a review
from `@DataDog/security-design-and-guidance`.
- [x] This PR doesn't touch any of that.

Co-authored-by: Emmett Butler <[email protected]>
Co-authored-by: Alberto Vara <[email protected]>

Author: 3 people

ddtrace/contrib/psycopg/async_cursor.py

@@ -19,10 +19,7 @@ async def __aexit__(self, exc_type, exc_val, exc_tb) -> None:
         # previous versions of the dbapi didn't support context managers. let's
         # reference the func that would be called to ensure that errors
         # messages will be the same.
-        await self.__wrapped__.__aexit__(exc_type, exc_val, exc_tb)
-
-        # and finally, yield the traced cursor.
-        return self
+        return await self.__wrapped__.__aexit__(exc_type, exc_val, exc_tb)
 
 
 class Psycopg3FetchTracedAsyncCursor(Psycopg3TracedAsyncCursor, dbapi_async.FetchTracedAsyncCursor):

releasenotes/notes/psycopg3-aexit-808941eef6191d86.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    psycopg: This fix resolves an issue where exceptions originating from asynchronous Psycopg cursors were not
+    propagated up the call stack.