remove not needed command

[utf18]

updating the package cache is IMHO not needed since the

--no-cache

option will pull directly from the online repos anyway.
(with the small benefit of around 1MB for the package cache)

if you do this to avoid caching of the layers while building i suggest to build with the --no-cache option from docker:
docker build --no-cache

All the best

[adrianchifor]

--no-cache has nothing to do with --update. Adding --update is the equivalent of running apk update, which is recommended before installing packages.

Just double checked online, you're right.

[utf18]

update just updates the local package cache i suppose

[adrianchifor]

Yes you're right, got confused for a second :) Thanks for the contribution!

[utf18]

you're welcome :)
sry for not be clear enough while proposing the change