Use "environment_version" instead of the deprecated "client" field (#109)

The scala-job template should use `"enviroment_version"` instead of the
deprecated `"client"` field.

Author: lennartkats-db

contrib/templates/scala-job/template/{{.project_name}}/resources/{{.project_name}}.job.yml.tmpl

@@ -12,6 +12,6 @@ resources:
       environments:
         - environment_key: default
           spec:
-            client: "4"
+            environment_version: "4"
             jar_dependencies:
                 - ${workspace.artifact_path}/.internal/{{.project_name}}-assembly-{{template `version` .}}.jar