set PRODUCT_VERSION for docker build (#14242)
set PRODUCT_VERSION for docker build (#14242)

Changes proposed in this PR:

In `actions-docker-build` we [pass](https://github.com/hashicorp/actions-docker-build/blob/05c370a26e61b06be46c5095d6e914c9f0ea4f3d/scripts/docker_build#L49) `PRODUCT_VERSION` to the docker build command. Since this was not set, the label did not populate properly which is used in a comparison to determine the `minor-latest` and `latest` docker image tags. 

How I've tested this PR:
 - build the image up to the point of label creation and pass in `--build-arg PRODUCT_VERSION=1.2.3`
 - inspect the image for the label with the above command

How I expect reviewers to test this PR:
- same as above

Related [internal-only] post about this: https://hashicorp.atlassian.net/wiki/spaces/RELENG/pages/2416934922/August+17+2022-+Docker+Build+Failures
hashicorp/consul,hashicorp/consul,hashicorp/consul,hashicorp/consul