Update authorities.csv

lib/uk_planning_scraper/authorities.csv

@@ -37,6 +37,7 @@ East Riding of Yorkshire,https://newplanningaccess.eastriding.gov.uk/newplanning
 Edinburgh,https://citydev-portal.edinburgh.gov.uk/idoxpa-web/search.do?action=advanced,scotland
 Enfield,https://planningandbuildingcontrol.enfield.gov.uk/online-applications/search.do?action=advanced,londonboroughs london
 Epsom and Ewell,http://eplanning.epsom-ewell.gov.uk/online-applications/search.do?action=advanced,surrey england
+Gateshead,https://public.gateshead.gov.uk/online-applications/search.do?action=advanced,england tyneandwear
 Glasgow,https://publicaccess.glasgow.gov.uk/online-applications/search.do?action=advanced,scotland
 Greenwich,https://planning.royalgreenwich.gov.uk/online-applications/search.do?action=advanced,london innerlondon southlondon england londonboroughs
 Hackney,http://planning.hackney.gov.uk/Northgate/PlanningExplorer/generalsearch.aspx,londonboroughs london