Set required golang to 1.21

[k0ste]

Fixes netdata/netdata#16278

[ilyam8]

Thanks, @k0ste!

[k0ste]

Added another commit, Run go get -u=patch ./... command for major version changes. Seems this also needed for golang

[ilyam8]

@k0ste please undo the last commit, it will break the plugin in a lot of places (e.g. won't compile on FreeBSD because wgctrl - cross-compilation no longer works with latest). I have dependabot setup and I update direct dependencies, if there is something is not up to date - it breaks the plugin or requires additional actions (e.g. regenerate generated code after updating radius).

[k0ste]

Understood, done. Do I need to do something for fix the CI pipeline issue?

[ilyam8]

@k0ste rebase onto the master, mysql testes were broken in master, just pushed a commit to fix them.

[k0ste]

Rebased