refactor: Use global.json for .NET version in GitHub Actions

Co-authored-by: pmaytak <[email protected]>

Author: Copilot

.github/workflows/dotnetcore.yml

@@ -9,23 +9,20 @@ jobs:
     name: Abstractions GitHub Action Test
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v5     
-    - name: Setup .NET 8.0.x
+      uses: actions/checkout@v5
+    
+    - name: Use .NET version from global.json
       uses: actions/setup-dotnet@v5
       with:
-        dotnet-version: 8.0.x
-
-    - name: Setup .NET 10.0.100
+        global-json-file: global.json
+    
+    - name: Setup .NET 8.0.x
       uses: actions/setup-dotnet@v5
       with:
-        dotnet-version: 10.0.100
+        dotnet-version: 8.0.x
 
     # Run the tests  
-    - name: Build with .NET 8.0.x
-      run: dotnet test -v m --configuration Release Microsoft.Identity.Abstractions.sln
-
-    # Run the tests  
-    - name: Build with .NET 10.0.100
+    - name: Build and test
       run: dotnet test -v m --configuration Release Microsoft.Identity.Abstractions.sln
 
     # Pack the library