fix: use repo.owner.login for security-updates URLs and handle datetime in created_after filter

## What/Why
Fix two bugs exposed by the PyGithub migration: (1) repo.owner is now a
NamedUser object, not a string, so security-updates URLs rendered as
"repos/NamedUser(login=...)/..." and 404'd silently; (2) repo.created_at
is a datetime object but is_repo_created_date_before called
fromisoformat() on it, which raises TypeError.

## Proof it works
All 180 tests pass including 2 new tests for datetime input to
is_repo_created_date_before (both before and after filter date).

## Risk + AI role
Medium -- the repo.owner.login fix touches the security-updates code
path which is pragma: no cover. AI-generated (Claude Opus 4.6) with
human review.

## Review focus
Whether repo.owner.login is the correct attribute for all PyGithub
Repository objects (org-owned vs user-owned repos).

Signed-off-by: jmeridth <jmeridth@gmail.com>

Author: jmeridth

evergreen.py

@@ -213,10 +213,10 @@ def main():  # pragma: no cover
         # Get dependabot security updates enabled if possible
         if config.enable_security_updates:
             if not is_dependabot_security_updates_enabled(
-                config.ghe, config.ghe_api_url, repo.owner, repo.name, token
+                config.ghe, config.ghe_api_url, repo.owner.login, repo.name, token
             ):
                 enable_dependabot_security_updates(
-                    config.ghe, config.ghe_api_url, repo.owner, repo.name, token
+                    config.ghe, config.ghe_api_url, repo.owner.login, repo.name, token
                 )
 
         if config.follow_up_type == "issue":
@@ -300,9 +300,16 @@ def main():  # pragma: no cover
     append_to_github_summary(summary_content)
 
 
-def is_repo_created_date_before(repo_created_at: str, created_after_date: str):
+def is_repo_created_date_before(
+    repo_created_at: str | datetime, created_after_date: str
+):
     """Check if the repository was created before the created_after_date"""
-    repo_created_at_date = datetime.fromisoformat(repo_created_at).replace(tzinfo=None)
+    if isinstance(repo_created_at, datetime):
+        repo_created_at_date = repo_created_at.replace(tzinfo=None)
+    else:
+        repo_created_at_date = datetime.fromisoformat(repo_created_at).replace(
+            tzinfo=None
+        )
     return created_after_date and repo_created_at_date < datetime.strptime(
         created_after_date, "%Y-%m-%d"
     )

test_evergreen.py

@@ -3,6 +3,7 @@
 
 import unittest
 import uuid
+from datetime import datetime, timezone
 from unittest.mock import MagicMock, patch
 
 import requests
@@ -801,6 +802,24 @@ def test_is_repo_created_date_is_before_created_after_date_without_timezone_agai
 
         self.assertTrue(result)
 
+    def test_is_repo_created_date_before_with_datetime_object(self):
+        """Test that a datetime object (as returned by PyGithub) is handled correctly."""
+        repo_created_at = datetime(2020, 1, 1, 5, 0, 0, tzinfo=timezone.utc)
+        created_after_date = "2021-01-01"
+
+        result = is_repo_created_date_before(repo_created_at, created_after_date)
+
+        self.assertTrue(result)
+
+    def test_is_repo_created_date_after_with_datetime_object(self):
+        """Test that a datetime object after the filter date returns False."""
+        repo_created_at = datetime(2022, 1, 1, 5, 0, 0, tzinfo=timezone.utc)
+        created_after_date = "2021-01-01"
+
+        result = is_repo_created_date_before(repo_created_at, created_after_date)
+
+        self.assertFalse(result)
+
     def test_is_repo_created_date_and_created_after_date_is_not_a_date(self):
         """Test the repo.created_at date and the created_after_date argument is not a date."""
         repo_created_at = "2018-01-01"