update api/4.json
update api/4.json

* update version in `api/4.json`

douglaskastle/bootswatch,nicolasmccurdy/bootswatch,nkraft/bootswatch,nkraft/bootswatch,thomaspark/bootswatch,nkraft/bootswatch,nicolasmccurdy/bootswatch,douglaskastle/bootswatch,nicolasmccurdy/bootswatch,douglaskastle/bootswatch,thomaspark/bootswatch,douglaskastle/bootswatch,thomaspark/bootswatch