Resolves #801 Upgrade csharp console apps to use .net core 3.1 (LTS) instead of the end of life .net core 2.2. (#803)

* Upgrade csharp benchmark, samples and tests console app projects to use dotnet core 3.1 (LTS) as opposed to the end of life dotnet core 2.2 (which less people will have installed)

* Update ci build for csharp to use .net core 3.1 (LTS) instead of the end of life .net core 2.2

Author: alexisatkinson

.github/workflows/ci.yml

@@ -47,7 +47,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        dotnet: [ '2.2.103' ]
+        dotnet: [ '3.1.301' ]
     env:
       DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
       DOTNET_CLI_TELEMETRY_OPTOUT: 1

csharp/sbe-benchmarks/sbe-benchmarks.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net45;netcoreapp2.2</TargetFrameworks>
+    <TargetFrameworks>net45;netcoreapp3.1</TargetFrameworks>
     <RootNamespace>Org.SbeTool.Sbe.Benchmarks</RootNamespace>
     <AssemblyName>Org.SbeTool.Sbe.Benchmarks</AssemblyName>
     <OutputTypeEx>exe</OutputTypeEx>

csharp/sbe-samples-car/sbe-samples-car.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net45;netcoreapp2.2</TargetFrameworks>
+    <TargetFrameworks>net45;netcoreapp3.1</TargetFrameworks>
     <OutputTypeEx>exe</OutputTypeEx>
     <RootNamespace>Org.SbeTool.Sbe.Example.Car</RootNamespace>
     <AssemblyName>Org.SbeTool.Sbe.Example.Car</AssemblyName>

csharp/sbe-tests/sbe-tests.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net45;netcoreapp2.2</TargetFrameworks>
+    <TargetFrameworks>net45;netcoreapp3.1</TargetFrameworks>
     <RootNamespace>Org.SbeTool.Sbe.Tests</RootNamespace>
     <AssemblyName>Org.SbeTool.Sbe.UnitTests</AssemblyName>
     <AllowUnsafeBlocks>True</AllowUnsafeBlocks>