fix yaml path in unified-search-app (microsoft#1873)

Author: dayesouza

unified-search-app/.vsts-ci.yml

@@ -7,7 +7,7 @@ trigger:
   branches:
     include:
       - main
-  path:
+  paths:
     include:
       - unified-search-app
 
@@ -37,4 +37,4 @@ stages:
             inputs:
               azureSubscription: '$(subscription)'
               Action: 'Restart Azure App Service'
-              WebAppName: '$(webApp)'
+              WebAppName: '$(webApp)'