`Update References` commits are not signed and trigger `integration-k8s-kind` CI during releasing

[NikitaSkrynnik]

Description

1. Update References workflow is triggered by PRs merged during releases. This behaviour triggers integration-k8s-kind CI
2. Commits created by Update References workflow are not signed

Solution

1. Remove automerge is completed trigger from Update References workflow.
2. Use GPG keys to sign commits

[NikitaSkrynnik]

Solutions for unsigned commits

1. Use GPG keys. Described here.
2. Make commits using Github API. In this case the commit's author will be github-actions[bot] (instead of nsmbot)