Release ecctl v1.13.0

[beiske]

Version to be released

Release ecctl v1.13.0

Checklist

The following actions must be performed in the order specified here.
For detailed instructions on all of the steps, read the release documentation.

• Update the cloud-sdk-go dependency.
• Check that the VERSION environment variable in the Makefile is updated and generate changelog.
• Execute the release.
• Modify the conf.yaml file in the docs repository to add the release branch.
• Run a full doc rebuild.
• Alert marketing team to update downloads website with new links.
• Celebrate 🎉