Add parsing helm version into module

[fsadykov]

Hello team,

Currently, We are not able to specify the version of the helm release. Please add one more variable to the terraform module so we can go ahead and parse the version of the application to helm release.

See what you need to add
https://www.terraform.io/docs/providers/helm/r/release.html#version

module "example" {
     source = "git::https://github.com/fuchicorp/terraform-helm-chart.git?ref=master"
     release_version = "v0.0.4" # we should be able to use this code 
}