chore: fix for 2.21 psycopg circular import (#13411)

Fix to the circular import with 2.21 an the psycopg2 contrib.

## Checklist
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- The change includes or references documentation updates if necessary
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[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
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---------

Signed-off-by: Juanjo Alvarez <[email protected]>

Author: juanjux

ddtrace/contrib/internal/psycopg/patch.py

@@ -5,7 +5,6 @@
 
 from ddtrace import config
 from ddtrace.contrib import dbapi
-from ddtrace.trace import Pin
 
 
 try:
@@ -116,6 +115,8 @@ def _patch(psycopg_module):
         return
     psycopg_module._datadog_patch = True
 
+    from ddtrace.trace import Pin
+
     Pin(_config=config.psycopg).onto(psycopg_module)
 
     if psycopg_module.__name__ == "psycopg2":
@@ -162,6 +163,8 @@ def _unpatch(psycopg_module):
             psycopg_module.Connection.connect = _original_connect
             psycopg_module.AsyncConnection.connect = _original_async_connect
 
+        from ddtrace.trace import Pin
+
         pin = Pin.get_from(psycopg_module)
         if pin:
             pin.remove_from(psycopg_module)
@@ -180,6 +183,8 @@ def init_cursor_from_connection(wrapped_cursor_cls, _, args, kwargs):
             if not connection:
                 return wrapped_cursor_cls(*args, **kwargs)
 
+        from ddtrace.trace import Pin
+
         pin = Pin.get_from(connection).clone()
         cfg = config.psycopg
 

releasenotes/notes/psycopg-circular-import-d30ca649d64fea78.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    Fix a potential circular import with the psycopg2 contrib.

tests/contrib/psycopg2/test_psycopg_patch.py

@@ -3,6 +3,8 @@
 # removed the ``_generated`` suffix from the file name, to prevent the content
 # from being overwritten by future re-generations.
 
+import pytest
+
 from ddtrace.contrib.internal.psycopg.patch import get_version
 from ddtrace.contrib.internal.psycopg.patch import get_versions
 from ddtrace.contrib.internal.psycopg.patch import patch
@@ -40,3 +42,17 @@ def test_and_emit_get_version(self):
         assert versions.get("psycopg2")
         emit_integration_and_version_to_test_agent("psycopg", versions["psycopg2"], "psycopg2")
         unpatch()
+
+
+def test_psycopg_circular_import():
+    import importlib
+    import sys
+
+    patch_module_name = "ddtrace.contrib.internal.psycopg.patch"
+    if patch_module_name in sys.modules:
+        del sys.modules[patch_module_name]
+
+    try:
+        importlib.import_module(patch_module_name)
+    except Exception as e:
+        pytest.fail(f"Failed to import psycopg patch module: {str(e)}")