refactor: update timestamp handling to use timezone-aware datetime

app/models/user_oauth.py

@@ -2,6 +2,7 @@
 
 from datetime import datetime
 from typing import TYPE_CHECKING, Optional
+from zoneinfo import ZoneInfo
 
 from sqlalchemy import DateTime, ForeignKey, String, Text
 from sqlalchemy.orm import Mapped, mapped_column, relationship
@@ -34,13 +35,13 @@ class UserOAuth(db.Model):
     # Timestamps
     created_at: Mapped[datetime] = mapped_column(
         DateTime,
-        default=datetime.utcnow,
+        default=lambda: datetime.now(tz=ZoneInfo("UTC")),
         nullable=False,
     )
     updated_at: Mapped[datetime] = mapped_column(
         DateTime,
-        default=datetime.utcnow,
-        onupdate=datetime.utcnow,
+        default=lambda: datetime.now(tz=ZoneInfo("UTC")),
+        onupdate=lambda: datetime.now(tz=ZoneInfo("UTC")),
         nullable=False,
     )
 
@@ -107,7 +108,7 @@ class UserOAuth(db.Model):
             oauth_provider.email = email
             oauth_provider.name = name
             oauth_provider.picture = picture
-            oauth_provider.updated_at = datetime.utcnow()
+            oauth_provider.updated_at = datetime.now(tz=ZoneInfo("UTC"))
         else:
             # Create new provider
             oauth_provider = cls(