The errors in `update-codegen.sh` are silenced

https://github.com/knative-extensions/knobots/blob/f15f57f3ccfa478ef136d536b108b1db08dd47c2/actions/update-deps/entrypoint.sh#L65

This line is probably buggy. In shell, if the whole line will be evaluated as conditional, and conditionals doesn't fail the script.

It most likely should be:

```sh
if [[ ! -f hack/update-codegen.sh ]]; then
  ./hack/update-codegen.sh
fi
``` 

/kind bug