Kubernetes how to make Deployment to update image

I do have deployment with single pod, with my custom docker image like:

containers:
  - name: mycontainer
    image: myimage:latest

During development I want to push new latest version and make Deployment updated.
Can’t find how to do that, without explicitly defining tag/version and increment it for each build, and do

kubectl set image deployment/my-deployment mycontainer=myimage:1.9.1