gdbus-codegen: upgraded package to upstream

Upgraded dev-util/gdbus-codegen to version 2.66.7 on amd64

I needed to add python3_6 compatibility for this to work.

Upstreamed in parallel: crrev/c/2718656

BUG=b/181107534
TEST=presubmit
RELEASE_NOTE=None

Change-Id: Ib4f3eda0d0e69a52fe761344cb3793799633617b
Reviewed-on: https://cos-review.googlesource.com/c/third_party/overlays/portage-stable/+/13110
Reviewed-by: Vaibhav Rustagi <vaibhavrustagi@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
3 files changed