WS-648: alembic script to add column to capability_versions

Adds workflow_metadata column of type json to archive.capability_versions

schema/versions/af3e4a4e7ede_add_ws_json_metadata_column_to_capab_.py

+"""add ws_metadata JSON column to capability_versions
+
+Revision ID: af3e4a4e7ede
+Revises: 42723a9dd85c
+Create Date: 2021-09-13 17:17:36.743665
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'af3e4a4e7ede'
+down_revision = '42723a9dd85c'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.execute("ALTER TABLE capability_versions ADD COLUMN IF NOT EXISTS ws_metadata JSON DEFAULT NULL")
+
+
+def downgrade():
+    op.execute("ALTER TABLE capability_versions DROP COLUMN IF EXISTS ws_metadata")