Use static base image

Removes openssl which doesn't get used anyway

Different issuers for root and leaf

Update go to 1.15 (#24)

* Update go to 1.15
* Update go dependencies

Set subject DN to load certificate into keystore (#20)

Update client-go to 0.18.5 (#22)

s390x (#16)

Fix incorrect error about 'ca'

Fix getting go version

Fix release process

Update .gitignore