Update dotnet in tests (3.1 -> 6.0)

Signed-off-by: Ivan Kochurkin <[email protected]>

Author: KvanTTT

.circleci/scripts/install-linux-csharp.sh

@@ -1,11 +1,11 @@
 #!/bin/bash
 
 echo "installing .Net SDK..."
-wget https://packages.microsoft.com/config/ubuntu/16.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
+wget https://packages.microsoft.com/config/ubuntu/20.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
 sudo dpkg -i packages-microsoft-prod.deb
+rm packages-microsoft-prod.deb
 sudo apt-get update; \
   sudo apt-get install -y apt-transport-https && \
   sudo apt-get update && \
-  sudo apt-get install -y dotnet-sdk-3.1
-export PATH=$PATH:~/.dotnet
+  sudo apt-get install -y dotnet-sdk-6.0
 echo "done installing .Net SDK"

.github/workflows/windows.yml

@@ -43,13 +43,11 @@ jobs:
       uses: actions/setup-node@v2
       with:
         node-version: '14'
-    - name: Setup Dotnet 3.1 and 5.0
+    - name: Setup Dotnet
       if: matrix.TARGET == 'csharp'
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: |
-          3.1.x
-          5.0.x
+        dotnet-version: '6.0.x'
 #     fails due to os (Linux only), use global install
 #    - name: Setup Dart 2.12.1
 #      uses: dart-lang/setup-dart@v1

runtime-testsuite/resources/org/antlr/v4/test/runtime/helpers/Antlr4.Test.csproj.stg

@@ -1,7 +1,7 @@
 \<Project Sdk="Microsoft.NET.Sdk">
 
   \<PropertyGroup>
-    \<TargetFramework>netcoreapp3.1\</TargetFramework>
+    \<TargetFramework>net6.0\</TargetFramework>
     \<NoWarn>$(NoWarn);CS3021\</NoWarn>
     \<AssemblyName>Test\</AssemblyName>
     \<OutputType>Exe\</OutputType>