no need for alpine base/cert CA bundle copy anymore

[ldemailly]

with #65 merged, you should remove

https://github.com/fortio/slack-proxy/blob/main/Dockerfile#L2-L3

as it's not needed anymore: eg see https://github.com/fortio/multicurl/pull/146/files#diff-dd2c0eb6ea5cfc6c4bd4eac30934e2d5746747af48fef6da689e85b752f39557

Originally posted by @ldemailly in #65 (comment)

[ani1311]

Okay got it. I'll clean it up.

[ldemailly]

I could make the MR myself (it's removing 3 lines) but wanted you guys to be aware of this shorter pure "from scratch" way

I wrote it up btw: https://laurentsv.com/blog/2024/06/25/stop-the-go-and-docker-madness.html