Deprecate arm and 386

AFAIK there are no computers in the market since almost a decade supporting those architectures. Can we drop support for them?

arm64 in raspberrypi was introduced in the version 3, in 2016.

From dockerhub's stadistics from last month. Out of 584 image downloads 1 was arm/v7 and 1 was 386. It doesn't look like they have much users.