How to increase dockerhub rate limits within kubeless?
A good start is to set the imagePullPolicy for your PodSpec to IfNotPresent, so that you'll only have to pull once per version per node.
Depending on the criticality of the workload you should also consider mirroring the image to a container registry you control. You don't want to be hitting rate limits when you need to roll out a hotfix at 3 AM.