Upgrade Database: Changing domain table type column to 8 chars

PowerDNS 4.7 is supporting 2 new zone types: "producer" & "consumer"
Due to the domain type column is limited to 6 chars, PDA Zone update will fail if producer or cusomer zones exist.
To solve this problem, this commit increases the lenght of the domain type column to 8 chars.

migrations/versions/f41520e41cee_update_domain_type_length.py

@@ -0,0 +1,31 @@
+"""update domain type length
+
+Revision ID: f41520e41cee
+Revises: 6ea7dc05f496
+Create Date: 2023-01-10 11:56:28.538485
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'f41520e41cee'
+down_revision = '6ea7dc05f496'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    with op.batch_alter_table('domain') as batch_op:
+        batch_op.alter_column('type',
+                              existing_type=sa.String(length=6),
+                              type_=sa.String(length=8))
+
+
+def downgrade():
+    with op.batch_alter_table('domain') as batch_op:
+        batch_op.alter_column('type',
+                              existing_type=sa.String(length=8),
+                              type_=sa.String(length=6))
+