Use Ubuntu 18 instead of 16 in AzP

AArnott · AArnott · commit 14272ce7edf4 · 2021-11-03T12:12:47.000-06:00
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
@@ -42,7 +42,7 @@ stages:
 
   - job: Linux
     pool:
-      vmImage: Ubuntu 16.04
+      vmImage: Ubuntu 18.04
     steps:
     - checkout: self
       clean: true
