fix(spp_farmer_registry_vocabularies): correct holder type namespace URI

The holder type vocabulary used urn:fao:wca:2020:holder-type but the
farm_details model and views filter on urn:openspp:vocab:holder-type,
causing the Holder Type dropdown to show no records.

Author: emjay0921

spp_farmer_registry_vocabularies/README.md

@@ -48,7 +48,7 @@ with FAO standards:
 - Commercial
 - Both
 
-#### Holder Type (`urn:fao:wca:2020:holder-type`)
+#### Holder Type (`urn:openspp:vocab:holder-type`)
 
 - Individual
 - Joint

spp_farmer_registry_vocabularies/data/vocab_holder_type.xml

@@ -2,7 +2,7 @@
 <odoo noupdate="1">
     <record id="vocab_holder_type" model="spp.vocabulary">
         <field name="name">Holder Type (FAO WCA 2020)</field>
-        <field name="namespace_uri">urn:fao:wca:2020:holder-type</field>
+        <field name="namespace_uri">urn:openspp:vocab:holder-type</field>
         <field name="version">2020</field>
         <field name="is_system">True</field>
         <field name="domain">agriculture</field>