Use global.json in CI

Author: andyleejordan

.github/workflows/ci-test.yml

@@ -30,10 +30,8 @@ jobs:
         with:
           cache: true
           cache-dependency-path: '**/*.csproj'
-          dotnet-version: |
-            6.0.x
-            7.0.x
-            8.0.x
+          dotnet-version: 6.0.x
+          global-json-file: "./global.json"
 
       - name: Install PSResources
         shell: pwsh

.pipelines/PowerShellEditorServices-Official.yml

@@ -80,7 +80,7 @@ extends:
             displayName: Use .NET 8.x SDK
             inputs:
               packageType: sdk
-              version: 8.x
+              useGlobalJson: true
           - task: UseDotNet@2
             displayName: Use .NET 6.x runtime (for tests)
             inputs: