Remove "ds:" in signed XML tree namespace in python's signxml

I am working with Python's lxml and signxml to generate an xml file and sign it with a pem certificate and private key.

I am required to validate the signed xml in the followign website validate XML. For some reason in this website the signed XML files with the "ds" namespace in signature tags do not recognize the file as signed.

I will not focus much on the generated xml file with lxml. The code to sign the xml file has the following form:

    def _get_xml_tree_root(self):
        root = ET.Element('facturaElectronicaCompraVenta' , attrib={location_attribute: invoice_sector + '.xsd'})
        xml_header = ET.SubElement(root, 'header')
        xml_detail = ET.SubElement(root, 'detail')
      return root

    def _get_signed_xml(self):
        signed_root = XMLSigner().sign(
            self._get_xml_tree_root(),
            key=base64.b64decode(io.TextIOWrapper(BytesIO(electronic_key)).read()),
            cert=base64.b64decode(io.TextIOWrapper(BytesIO(electronic_certificate)).read())
        )
        return signed_root

The problem is that the xml file that I generate in the signature section has following form:

<facturaElectronicaCompraVenta xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="facturaElectronicaCompraVenta.xsd">
   <header></header>
   <detail></detail>
    <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
        <ds:SignedInfo>
            <ds:CanonicalizationMethod Algorithm="http://www.w3.org/2006/12/xml-c14n11"/>
            <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/>
            <ds:Reference URI="">
                <ds:Transforms>
                    <ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
                    <ds:Transform Algorithm="http://www.w3.org/2006/12/xml-c14n11"/>
                </ds:Transforms>
                <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
                <ds:DigestValue>KvIMPxajMb98G3+HdSLg1/pgSyisLp4OWZt6Gxhe+/c=</ds:DigestValue>
            </ds:Reference>
        </ds:SignedInfo>
        <ds:SignatureValue>Bv9W9cGyXvX4QeDDb61YME8TbnFlBOVBw2Iiv+a+7VrxjoH4z8kLO4rgonXbqGuk2DKrR4ACqoFQNd/9/lJb31TDk2SjegURBsjP9gLvFWwfq99jh6zn6rPF/gwqd+lA1ruGpDT/Q+vxMXeNpXfk+nDcgdDJoP1bpDEPHbSHGkQu2SX1NQP1SlRZkNoJXxorFfbTDmm1/VFRsv5uBNQvf7hSxTEvvLW8WVYN271iTzHTpAnbyg7VTeys/Ca2FQsZ95hgCHfKsOHEX2/HtxpkGtXDjJKPHq43M2MR3Bp9+YUBAxcj5WMsGcs0lp7hFP6xADEJAcLdfta3SJCdNTa0Vw==</ds:SignatureValue>
        <ds:KeyInfo>
            <ds:X509Data>
                <ds:X509Certificate>
                   CertificateStuff...
                </ds:X509Certificate>
            </ds:X509Data>
        </ds:KeyInfo>
    </ds:Signature>
</facturaElectronicaCompraVenta>

I need to sign the xml file without the "ds" namespace like the following:

<facturaElectronicaCompraVenta xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="facturaElectronicaCompraVenta.xsd">
   <header></header>
   <detail></detail>
   <Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
       <SignedInfo>
           <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
           <SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/>
           <Reference URI="">
               <Transforms>
                   <Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
                   <Transform Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments"/>
               </Transforms>
               <DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
            <DigestValue>WmFvnKBZIr9D37PaYuxM3aoXVu9nDZT+2MI1I+RUh8s=  </DigestValue>
       </Reference>
       </SignedInfo>
       <SignatureValue> itb123fGGhh12DpFDFas34ASDAPpSSSSadasDasAS1smkRsj5ksdjasd8asdkasjd8asdkas8asdk21v a1qf+kBKLwF39mj+5zKo1qf+kBKLD42qD/+yxSMMS6DM5SywPxO1oyjnSZtObIe/45fdS4sE9+aNOn UncYUlSDAPpSSSSadasgIMWwlX2XMJ4SDAPpSSSSadas6qihJt/3dEIdta1RETSDAPpSSSSadas9S2W ALbT3VV8pjLqikVLcSDAPpSSSSadaseCKG8abcdssM0Wm8p+5grNNpSDAPpSSSSadasy4TvT4C3xS 70zSbKWeBUUglRcU8FECEcacu+UJaBCgRW0S3Q== </SignatureValue>
       <KeyInfo>
           <X509Data>
               <X509Certificate>
                  CertificateStuff..
               </X509Certificate>
           </X509Data>
       </KeyInfo>
   </Signature>
</facturaElectronicaCompraVenta>

I not sure why the site do not recognize the signature with the "ds:" namespace. I have previously struggled with xml namespaces and I do not understand them very well.

But, how could I sign the XML file without the "ds:" namespace without changing the signxml library source code?

from Remove "ds:" in signed XML tree namespace in python's signxml