[ci] Use the new "main" default branch (#100)

brendanzagaeski · web-flow · commit ad80a42950f4 · 2020-12-15T16:28:35.000-05:00
The main branch is now the default branch, we need to update CI triggers
accordingly.
diff --git a/azure-pipelines.yaml b/azure-pipelines.yaml
@@ -1,11 +1,11 @@
 name: Xamarin.Android.Tools $(Rev:r)
 
 trigger:
-  - master
+  - main
   - d16-*
 
 pr:
-  - master
+  - main
   - d16-*
 
 # Global variables
