Update support message and placement, upgrade external packages for building on M1

Changelog for 0.12.1:

Commits
386e158 Alter the support message printed in k3sup by @alexellis
7a56f29 Increase minimum 32-bit arm version by @alexellis
68217ee Upgrade golang.org packages by @alexellis
5f9113d Update ISSUE_TEMPLATE.md by @alexellis

Changes: 0.12.0...0.12.1

Generated by Derek