Fix kramdown CVE-2020-14001
Fix kramdown CVE-2020-14001

https://github.com/advisories/GHSA-mqm2-cgpr-p4m6

Run "bundle update" and upgrade most ruby gems.

Signed-off-by: Fabio Utzig <382671175562e0df8128054dbdb05a250d79f588@nordicsemi.no>

tamban01/mcuboot,utzig/mcuboot,ATmobica/mcuboot,utzig/mcuboot,ATmobica/mcuboot,tamban01/mcuboot,ATmobica/mcuboot,runtimeco/mcuboot,tamban01/mcuboot,utzig/mcuboot,ATmobica/mcuboot,runtimeco/mcuboot,utzig/mcuboot,tamban01/mcuboot,runtimeco/mcuboot,utzig/mcuboot,ATmobica/mcuboot,runtimeco/mcuboot,tamban01/mcuboot,runtimeco/mcuboot