refac: deprecate peewee migration layer

The Alembic init migration (7e5b5dc7342b) already creates the
equivalent schema. Peewee migrations are no longer needed for
any version >= 0.3.6.

backend/open_webui/migrations/versions/ca81bd47c050_add_config_table.py

@@ -1,9 +1,8 @@
-"""Add config table
+"""Add config table.
 
 Revision ID: ca81bd47c050
 Revises: 7e5b5dc7342b
 Create Date: 2024-08-25 15:26:35.241684
-
 """
 
 from typing import Sequence, Union
@@ -11,22 +10,27 @@ from typing import Sequence, Union
 import sqlalchemy as sa
 from alembic import op
 
-# revision identifiers, used by Alembic.
-revision: str = 'ca81bd47c050'
-down_revision: Union[str, None] = '7e5b5dc7342b'
+revision: str = "ca81bd47c050"
+down_revision: Union[str, None] = "7e5b5dc7342b"
 branch_labels: Union[str, Sequence[str], None] = None
 depends_on: Union[str, Sequence[str], None] = None
 
 
-def upgrade():
+def upgrade() -> None:
+    """Create a key-value config table with versioning."""
     op.create_table(
-        'config',
-        sa.Column('id', sa.Integer, primary_key=True),
-        sa.Column('data', sa.JSON(), nullable=False),
-        sa.Column('version', sa.Integer, nullable=False),
-        sa.Column('created_at', sa.DateTime(), nullable=False, server_default=sa.func.now()),
+        "config",
+        sa.Column("id", sa.Integer, primary_key=True),
+        sa.Column("data", sa.JSON(), nullable=False),
+        sa.Column("version", sa.Integer, nullable=False),
         sa.Column(
-            'updated_at',
+            "created_at",
+            sa.DateTime(),
+            nullable=False,
+            server_default=sa.func.now(),
+        ),
+        sa.Column(
+            "updated_at",
             sa.DateTime(),
             nullable=True,
             server_default=sa.func.now(),
@@ -35,5 +39,6 @@ def upgrade():
     )
 
 
-def downgrade():
-    op.drop_table('config')
+def downgrade() -> None:
+    """Drop the config table."""
+    op.drop_table("config")