Update build scripts to .NET Core 3.1

Author: henkmollema

.appveyor.yml

@@ -2,12 +2,8 @@ version: '{build}'
 pull_requests:
   do_not_increment_build_number: true
 image: Visual Studio 2019
-nuget:
-  disable_publish_on_pr: true
 build_script:
-  - cmd: dotnet build
   - cmd: dotnet test .\test\Webenable.Logging.JavaScript.Tests
-  - cmd: dotnet pack .\src\Webenable.Logging.JavaScript -c Release -o .\artifacts
 test: off
 branches:
   only:
@@ -16,8 +12,4 @@ init:
   - git config --global core.autocrlf input
 environment:
   DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
-  DOTNET_CLI_TELEMETRY_OPTOUT: true
-  CI: true
-artifacts:
-- path: .\artifacts\**\*.nupkg
-  name: NuGet
+  DOTNET_CLI_TELEMETRY_OPTOUT: true

.travis.yml

@@ -1,6 +1,6 @@
 language: csharp
 mono: none
-dotnet: 3.0
+dotnet: 3.1
 dist: xenial
 env:
   global:
@@ -10,12 +10,4 @@ branches:
   only:
   - master
 script:
-    - dotnet build
-    - dotnet test test/Webenable.Logging.JavaScript.Tests
-matrix:
-  include:
-    - os: linux
-      dist: xenial
-    - os: osx
-      dotnet: 3.0.100
-      osx_image: xcode11.2
+    - dotnet test test/Webenable.Logging.JavaScript.Tests