Fix error in old migrations caused by dependency updates

migrations/versions/dff4b87e4a76_.py

@@ -7,6 +7,7 @@ Create Date: 2020-07-17 23:47:51.096874
 """
 import sqlalchemy as sa
 from alembic import op
+from sqlalchemy import text
 
 # revision identifiers, used by Alembic.
 revision = 'dff4b87e4a76'
@@ -19,9 +20,9 @@ def upgrade():
 	# ### commands auto generated by Alembic - please adjust! ###
 	op.add_column('package', sa.Column('approved_at', sa.DateTime(), nullable=True, server_default=None))
 
-	op.execute("""
+	op.execute(text("""
 		UPDATE package SET approved_at=created_at WHERE approved;
-	""")
+	"""))
 	# ### end Alembic commands ###