(build) use only the latest LTS - 3.1

Author: arturcic

azure-pipelines.yml

@@ -60,7 +60,7 @@ stages:
       name: Linux
       vmImage: 'ubuntu-latest'
       distros: [ 'alpine.3.10-x64', 'centos.7-x64', 'debian.9-x64', 'fedora.30-x64', 'ubuntu.16.04-x64', 'ubuntu.18.04-x64' ]
-      dotnetVersions: [ '2.1', '3.1' ]
+      dotnetVersions: [ '3.1' ]
 
 - stage: Docker
   displayName: 'Docker Build & Test'
@@ -72,7 +72,7 @@ stages:
       name: Linux
       vmImage: 'ubuntu-latest'
       distros: [ 'alpine.3.10-x64', 'centos.7-x64', 'debian.9-x64', 'fedora.30-x64', 'ubuntu.16.04-x64', 'ubuntu.18.04-x64' ]
-      dotnetVersions: [ '2.1', '3.1' ]
+      dotnetVersions: [ '3.1' ]
 
 - stage: Publish
   displayName: 'Publish'