Extend the existing CI pipeline

- Add .NET 5, 6, & 7
- Add Windows and macOS
- Update NuGet packages for tests

.github/workflows/dotnet.yml

@@ -0,0 +1,40 @@
+name: .NET
+
+on: [push, pull_request]
+
+env:
+  DOTNET_CLI_TELEMETRY_OPTOUT: 1
+
+jobs:
+  build:
+    name: ${{ matrix.platform.name }} ${{ matrix.dotnet.name }}
+    runs-on: ${{ matrix.platform.os }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        platform:
+          - { name: Linux, os: ubuntu-22.04 }
+          - { name: Windows, os: windows-2022 }
+          - { name: macOS, os: macos-12 }
+        dotnet:
+          - { name: .NET Core 3.1, version: "3.1" }
+          - { name: .NET 5, version: "5.0.x" }
+          - { name: .NET 6, version: "6.0.x" }
+          - { name: .NET 7, version: "7.0.x" }
+
+    steps:
+      - uses: actions/checkout@v3
+      - name: Setup .NET ${{ matrix.dotnet.version }} SDK
+        uses: actions/setup-dotnet@v3
+        with:
+          dotnet-version: ${{ matrix.dotnet.version }}
+      - name: Enforce SDK Version
+        run: dotnet new globaljson --sdk-version ${{ steps.setup-dotnet.outputs.dotnet-version }} --force
+      - name: Verify SDK Installation
+        run: dotnet --info
+      - name: Build
+        run: dotnet build ./Sources -c Release
+      - name: Test
+        if: matrix.dotnet.version == '6.0.x'
+        run: dotnet test ./Sources -v n --no-restore --no-build -c Release

Sources/DotNetGraph.Tests/DotNetGraph.Tests.csproj

@@ -1,16 +1,19 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>netcoreapp3.1</TargetFramework>
+        <TargetFramework>net6.0</TargetFramework>
 
         <IsPackable>false</IsPackable>
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.4.0" />
-        <PackageReference Include="NFluent" Version="2.6.0" />
-        <PackageReference Include="xunit" Version="2.4.1" />
-        <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.7.0" />
+        <PackageReference Include="NFluent" Version="3.0.1.352" />
+        <PackageReference Include="xunit" Version="2.5.0" />
+        <PackageReference Include="xunit.runner.visualstudio" Version="2.5.0">
+          <PrivateAssets>all</PrivateAssets>
+          <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+        </PackageReference>
     </ItemGroup>
 
     <ItemGroup>