fix: ensure is_active is true

[betodealmeida]

For some reason the CLI is pushing is_active=null to the API when updating columns, something that should never happen:

ERROR: preset_cli.lib: {"message":{"columns":{"0":{"is_active":["Field may not be null."]},"1":{"is_active":["Field may not be null."]},"2":{"is_active":["Field may not be null."]},"3":{"is_active":["Field may not be null."]},"4":{"is_active":["Field may not be null."]},"5":{"is_active":["Field may not be null."]}}}} 

I changed the CLI so that when a column has is_active set to None we remove it from the update, preserving the existing value.