Automatic merge from submit-queue

Insert Cynerva and Kjackal to approvers list

**What this PR does / why we need it**:
Per the membership reviews, we're looking to promote Konstantinos and
George to approvers to help distribute the review/bug load for the `cluster/juju` code
tree.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: 

**Special notes for your reviewer**:
cc @marcoceppi and @tvansteenburgh 

**Release note**:

```release-note
NONE
```