feat: add global.json to use latest SDK (#479)

Add a
[global.json](https://learn.microsoft.com/en-us/dotnet/core/tools/global-json)
file to keep the used
[SDK](https://dotnet.microsoft.com/en-us/download/dotnet) up-to-date.

.github/workflows/ci.yml

@@ -116,6 +116,13 @@ jobs:
         uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
         with:
           fetch-depth: 0
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: |
+            6.0.x
+            7.0.x
+            8.0.x
       - name: Setup MSBuild
         uses: microsoft/setup-msbuild@v2
       - name: Setup VSTest

.github/workflows/release.yml

@@ -164,6 +164,13 @@ jobs:
         run: |
           version="${GITHUB_REF#refs/heads/release/}"
           git tag "${version}"
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: |
+            6.0.x
+            7.0.x
+            8.0.x
       - name: Setup MSBuild
         uses: microsoft/setup-msbuild@v2
       - name: Setup VSTest

Testably.Abstractions.sln

@@ -13,6 +13,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "_", "_", "{94F99274-3518-45
 		Directory.Build.props = Directory.Build.props
 		Directory.Packages.props = Directory.Packages.props
 		Feature.Flags.props = Feature.Flags.props
+		global.json = global.json
 		LICENSE = LICENSE
 		nuget.config = nuget.config
 		README.md = README.md

global.json

@@ -0,0 +1,6 @@
+{
+	"sdk": {
+		"version": "8.0.201",
+		"rollForward": "latestMinor"
+	}
+}