Fix Black formatting issues

- Format singleton tests and repository implementation
- Ensure all files meet Black formatting requirements

Author: ahmadhasan2k8

src/patterns/repository.py

@@ -710,7 +710,7 @@ def _init_db(self):
             conn = self._connection
         else:
             conn = sqlite3.connect(self.db_path)
-            
+
         conn.execute(
             """
             CREATE TABLE IF NOT EXISTS users (
@@ -722,7 +722,7 @@ def _init_db(self):
         """
         )
         conn.commit()
-        
+
         # Only close if not in-memory
         if self.db_path != ":memory:":
             conn.close()
@@ -733,7 +733,7 @@ def _get_connection(self):
             return self._connection
         else:
             return sqlite3.connect(self.db_path)
-    
+
     def _close_connection(self, conn):
         """Close database connection if not persistent."""
         if not self._connection:

tests/test_patterns/test_singleton.py

@@ -21,6 +21,7 @@
 @singleton
 class SerializableService:
     """Test service for serialization testing."""
+
     def __init__(self):
         self.data = "test"