Fix bitbucket upstreams

[laverya]

What I Did

Updated go-getter to include a fix for bitbucket upstreams, as https://github.com/hashicorp/go-getter/issues/183 has been resolved by https://github.com/hashicorp/go-getter/pull/189.

How I Did it

How to verify it

Bitbucket upstream unit tests have been reincluded.

Description for the Changelog

Bitbucket upstreams are once again supported

Picture of a Ship (not required but encouraged)

[laverya]

So it looks like the istio failures are legitimate failures, and not something that's happening randomly I'll have to investigate this further