Update azure-pipelines.yml for Azure Pipelines

Author: davidbritch

azure-pipelines.yml

@@ -20,13 +20,10 @@ steps:
 
 - task: NuGetToolInstaller@1
 
-- task: NuGetCommand@2
-  inputs:
-    restoreSolution: '**/*.sln'
-
 - task: XamariniOS@2
   inputs:
-    solutionFile: '**/*.sln'
+    solutionFile: '**/*iOS.csproj'
     configuration: 'Debug'
+    runNugetRestore: true
     buildForSimulator: true
     packageApp: false