Update macOS image on Azure Pipelines

AArnott · web-flow · commit 1b9656883bd8 · 2020-03-02T07:49:40.000-07:00
This resolves the warning we see on Azure Pipelines about the soon-to-be-removed image.
diff --git a/azure-pipelines/build.yml b/azure-pipelines/build.yml
@@ -17,7 +17,7 @@ jobs:
 
 - job: macOS
   pool:
-    vmImage: macOS 10.13
+    vmImage: macOS-10.15
   steps:
   - template: install-dependencies.yml
   - template: dotnet.yml
