device_templates.py: attach_to_template fails when two variable names are similar

[robertdemeyer]

Dear Team,

I´ve faced an issue where a similar variable caused an deployment error when trying to attach a device to a devicetemplate.
The naming is not enforced to be unique inside the vManage GUI and the function in the SDK takes the none unique variable name rather the unique "property" field.

for entry in template_variables['columns']:
                if entry['variable']:
                    if **entry['variable']** in uuid[device_uuid]['variables']:
                        device_template_variables[entry['property']] = uuid[device_uuid]['variables'][**entry['variable']**]
                    else:
                        raise Exception(f"{entry['variable']} is missing for template {uuid[device_uuid]['host_name']}")