dyn_dns: Enable EDNS subnet processing for more accurate geodns

The EDNS Client Subnet header can provide a more accurate location of
the client, especially if the client is not near the recursive resolver,
so use it if it's provided.

roles/geo_dns/templates/pdns.conf.j2

@@ -9,3 +9,4 @@ geoip-database-files=/var/lib/GeoIP/GeoLite2-City.mmdb
 geoip-zones-file=/etc/powerdns/geo.yml
 enable-lua-records
 lua-health-checks-interval=60
+edns-subnet-processing=yes