Add schedule trigger to vcpkg pipeline

.azure/azure-pipelines-vcpkg.yml

@@ -19,6 +19,14 @@ parameters:
   type: boolean
   default: true
 
+schedules:
+- cron: "0 0 * * 1"
+  displayName: 'Weekly Monday Midnight build without caching'
+  branches:
+    include:
+    - master
+  always: true
+
 variables:
   toolset: 'v142'
   generator: 'Visual Studio 16 2019'