/vms/list post - filtering a VM which is case sensitive

I am passing this payload to to filter a VM. It works if the VM name is an exact match (case sensitive).  How Do I make the following filter case insensitive ?

payload = {"kind":"vm", "filter": "vm_name=={0}".format(vmName)}

I tried different combination’s, but none worked.

Thanks in Advance

Yezdi