Move https://github.com/pjbgf/git2go to fluxcd/git2go

[pjbgf]

Create an official fork for git2go.

Tasks:

• Copy changes from https://github.com/pjbgf/git2go
• Point all references to fluxcd/git2go.
  • build: Replace git2go with fluxcd fork #364
  • Update dependencies source-controller#919
  • Update dependencies image-automation-controller#442